Compiler Issue

When using qbasic and I try to compile a program I wrote, it has the error:
0030 0560 SCREEN 13
^ Data-memory Overflow

I can't compile my program because of this error, does anyone knw how to fix it. Oh and it only occurs when I am compiling a certain program. The program is a 3d missle flying across the screen.


the code for the program is:

'************************************************
'************************************************
DECLARE SUB zbuffer ()
DECLARE SUB bcls ()
DECLARE SUB Trans (theta!, phi!, delta!, pts!)
DECLARE SUB define ()
DECLARE SUB polyfill (p1!, p2!, p3!, c%)
DIM SHARED c(360), s(360), xc, yc, zc
DIM SHARED b(4000) AS LONG
DECLARE SUB bcopy ()
DECLARE SUB BPSET (x&, y&, COLOUR%)
DIM SHARED Buffer(32002) AS INTEGER

'INPUT "3d File: ", file$
file$ = "missle.dat"
SCREEN 13
GET (0, 0)-(319, 199), Buffer

OPEN file$ FOR INPUT AS #1
INPUT #1, xc
INPUT #1, yc
INPUT #1, zc
INPUT #1, pts
DIM SHARED x(pts), y(pts), z(pts), x2(pts), y2(pts), z2(pts), x3&(pts), y3&(pts)
DIM SHARED pols
FOR i = 1 TO pts
INPUT #1, x(i)
INPUT #1, y(i)
INPUT #1, z(i)
NEXT
INPUT #1, pols
DIM SHARED poly(3, pols), cpoly%(pols)
DIM SHARED zb(pols, 2)

FOR i = 1 TO pols
INPUT #1, poly(1, i)
INPUT #1, poly(2, i)
INPUT #1, poly(3, i)
INPUT #1, cpoly%(i)
NEXT

CLOSE #1


define
theta = 45
phi = 45 + 90
delta = 360
DO
delta = (delta + 12) MOD 360
theta = (theta + 0) MOD 360
phi = (phi + 0) MOD 360
CALL Trans(theta, phi, delta, pts)
CALL zbuffer
zc = zc + 1
xc = xc + 200 / zc
yc = yc + 100 / zc
bcopy
bcls
LOOP UNTIL INKEY$ = CHR$(27) OR xc > 300

SUB bcls
a& = Buffer(0)
b& = Buffer(1)
ERASE Buffer
Buffer(0) = a&
Buffer(1) = b&
END SUB

SUB bcopy
PUT (0, 0), Buffer, PSET
END SUB

SUB BPSET (xa&, ya&, c%)
W& = Buffer(0) / 8
O& = VARPTR(Buffer(2))
offset& = (W& * ya& + xa&) + O&
DEF SEG = VARSEG(Buffer(0)) + INT(offset& / 16)
POKE offset& MOD 16, c%
DEF SEG
END SUB

SUB define
FOR i = 0 TO 360
c(i) = COS(i * 3.14 / 180)
s(i) = SIN(i * 3.14 / 180)
NEXT
END SUB

SUB polyfill (p1, p2, p3, c%)
DIM xp(3), yp(3)
xp(1) = x3&(p1)
xp(2) = x3&(p2)
xp(3) = x3&(p3)
yp(1) = y3&(p1)
yp(2) = y3&(p2)
yp(3) = y3&(p3)
FOR i = 1 TO 3
FOR j = 1 TO 3
IF yp(i) < yp(j) THEN
sav = yp(i)
yp(i) = yp(j)
yp(j) = sav
sav = xp(i)
xp(i) = xp(j)
xp(j) = sav
END IF
NEXT
NEXT
IF yp(3) <> yp(1) THEN
sy1 = 1 / (yp(3) - yp(1))
ELSE
sy1 = 1
END IF
IF yp(2) <> yp(1) THEN
sy2 = 1 / (yp(2) - yp(1))
ELSE
sy2 = 1
END IF
IF yp(3) <> yp(2) THEN
sy3 = 1 / (yp(3) - yp(2))
ELSE
sy3 = 1
END IF
sx1 = xp(3) - xp(1)
sx2 = xp(2) - xp(1)
sx3 = xp(3) - xp(2)
FOR y = yp(1) TO yp(3)
IF y <= yp(2) THEN
x1 = INT((y - yp(1)) * sy1 * sx1 + xp(1))
x2 = INT((y - yp(1)) * sy2 * sx2 + xp(1))
IF x2 < x1 THEN
sav = x1
x1 = x2
x2 = sav
END IF
ya& = y
FOR xa& = x1 TO x2
offset = INT((320 * ya& + xa&) / 16) + 1
byte = (320 * ya& + xa&) MOD 16
a = b(offset) AND 2 ^ byte
IF a = 0 THEN
b(offset) = b(offset) OR 2 ^ byte
BPSET xa&, ya&, c%
END IF

NEXT
ELSE
x1 = INT((y - yp(1)) * sy1 * sx1 + xp(1))

x2 = INT((y - yp(2)) * sy3 * sx3 + xp(2))

IF x2 < x1 THEN
sav = x1
x1 = x2
x2 = sav
END IF
ya& = y
FOR xa& = x1 TO x2
offset = INT((320 * ya& + xa&) / 16) + 1
byte = (320 * ya& + xa&) MOD 16
a = b(offset) AND 2 ^ byte
IF a = 0 THEN
b(offset) = b(offset) OR 2 ^ byte
BPSET xa&, ya&, c%
END IF

NEXT
END IF
NEXT
END SUB

SUB Trans (theta, phi, delta, pts)
t = theta
p = phi
d = delta
a = c(p) * c(d)
b = c(p) * s(d)
c = (s(p) * s(t) * c(d) - c(t) * s(d))
de = (s(p) * s(t) * s(d) + c(t) * c(d))
e = c(p) * s(t)
f = (s(p) * c(t) * c(d) + s(t) * s(d))
g = (s(p) * c(t) * s(d) - s(d) * c(d))
h = c(p) * c(t)
FOR i = 1 TO pts
x2(i) = x(i) * a + y(i) * b - z(i) * s(p)
y2(i) = x(i) * c + y(i) * de + z(i) * e
z2(i) = x(i) * f + y(i) * g + z(i) * h

x3&(i) = 256 * (x2(i) / (z2(i) + zc)) + xc
y3&(i) = 200 - (256 * (y2(i) / (z2(i) + zc)) + yc)
BPSET x3&(i), y3&(i), 15
NEXT
END SUB

SUB zbuffer
ERASE b
FOR i = 1 TO pols
zb(i, 1) = z2(poly(1, i)) + z2(poly(2, i)) + z2(poly(3, i))
zb(i, 2) = i
NEXT
FOR i = 1 TO pols
FOR j = 1 TO pols
IF zb(i, 1) < zb(j, 1) THEN
sav = zb(i, 2)
zb(i, 2) = zb(j, 2)
zb(j, 2) = sav
sav = zb(i, 1)
zb(i, 1) = zb(j, 1)
zb(j, 1) = sav

END IF
NEXT
NEXT
FOR i = 1 TO pols
a = poly(1, zb(i, 2))
b = poly(2, zb(i, 2))
c = poly(3, zb(i, 2))
polyfill a, b, c, cpoly%(zb(i, 2))
NEXT
END SUB



'*********************************
'*********************************



The Data file "missle.dat" contains this:


80
70
50
57
0 0 -11
0 1 -10
0.71 0.71 -10
1 0 -10
0.71 -0.71 -10
0 -1 -10
-0.71 -0.71 -10
-1 0 -10
-0.71 0.71 -10
0 2 -8
1.41 1.41 -8
2 0 -8
1.41 -1.41 -8
0 -2 -8
-1.41 -1.41 -8
-2 0 -8
-1.41 1.41 -8
0 2 -7
1.41 1.41 -7
2 0 -7
1.41 -1.41 -7
0 -2 -7
-1.41 -1.41 -7
-2 0 -7
-1.41 1.41 -7
0 2 8
1.41 1.41 8
2 0 8
1.41 -1.41 8
0 -2 8
-1.41 -1.41 8
-2 0 8
-1.41 1.41 8
0 2 13
1.41 1.41 13
2 0 13
1.41 -1.41 13
0 -2 13
-1.41 -1.41 13
-2 0 13
-1.41 1.41 13
0 2 14
1.41 1.41 14
2 0 14
1.41 -1.41 14
0 -2 14
-1.41 -1.41 14
-2 0 14
-1.41 1.41 14
0 4 10
4 0 10
0 -4 10
-4 0 10
0 4 14
4 0 14
0 -4 14
-4 0 14
95
1 2 3 20
1 3 4 21
1 4 5 22
1 5 6 23
1 6 7 22
1 7 8 21
1 8 9 20
2 10 11 21
2 3 11 21
3 11 12 22
3 4 12 22
4 12 13 23
4 5 13 23
5 13 14 24
5 6 14 24
6 14 15 24
6 7 15 24
7 15 16 23
7 8 16 23
8 16 17 22
8 9 17 22
9 17 10 21
9 2 10 21
10 18 19 4
10 11 19 4
11 19 20 4
11 12 20 4
12 20 21 4
12 13 21 4
13 21 22 4
13 14 22 4
14 22 23 4
14 15 23 4
15 23 24 4
15 16 24 4
16 24 25 4
16 17 25 4
17 25 18 4
17 10 18 4
18 26 27 21
18 19 27 21
19 27 28 22
19 20 28 22
20 28 29 23
20 21 29 23
21 29 30 24
21 22 30 24
22 30 31 24
22 23 31 24
23 31 32 23
23 24 32 23
24 32 33 22
24 25 33 22
25 33 26 21
25 18 26 21
26 34 35 22
26 27 35 22
27 35 36 23
27 28 36 23
28 36 37 24
28 29 37 24
29 37 38 25
29 30 38 25
30 38 39 25
30 31 39 25
31 39 40 24
31 32 40 24
32 40 41 23
32 33 41 23
33 41 34 22
33 26 34 22
34 42 43 4
34 35 43 4
35 43 44 4
35 36 44 4
36 44 45 4
36 37 45 4
37 45 46 4
37 38 46 4
38 46 47 4
38 39 47 4
39 47 48 4
39 40 48 4
40 48 49 4
40 41 49 4
41 49 42 4
41 34 42 4
26 50 54 15
26 54 42 20
28 51 55 15
28 55 44 20
30 52 56 15
30 56 46 20
32 53 57 15
32 57 48 20