Exclude null and empty dates from chart

[RobHVB6Sql]

I have created a formula to chart a set of dates by month, although the null dates show up on the chart.
What do I need to do to this formula to exclude these from the chart?

//Formula starts here
if {q1stContact-Numbers.DateOfFirstContact} < cdate('01/01/1990 0:00:0')
and IsNull({q1stContact-Numbers.DateOfFirstContact}) = false
then
{q1stContact-Numbers.DateOfFirstContact}

I have also tried the order option in the Chart Expert. Rob Hasard
Data Manager -Genetic Services
(VB6 /SQL 7.0)

 

[Hillary]

I had a similar problem with dates and I had to use both the IsNull and Date(0,0,0) function to get mine to work. Try...

//Formula starts here
if {q1stContact-Numbers.DateOfFirstContact} < cdate('01/01/1990 0:00:0')
and IsNull({q1stContact-Numbers.DateOfFirstContact}) = false or
if {q1stContact-Numbers.DateOfFirstContact} < cdate('01/01/1990 0:00:0')
and ({q1stContact-Numbers.DateOfFirstContact}=Date(0,0,0)) = false
then
{q1stContact-Numbers.DateOfFirstContact}