Hi PHV and combo,
Thanks very much for your guys inputs!
I changed " Range(Cells(a, 1), Cells(l, b)).Select"
to "Range(Cells(1, 1), Cells(b, 12)).Select", and it works now!
However, when I changed it as " Range(Cells(a, A), Cells(l, L)).Select" it stuck again and shows the same prompt as...