Having Trouble with Autofilling Across Columns

Hi all,

I am having an issue with a formula. I would like to have this formula in C4:
=IF(VLOOKUP(C$1, PasteSheet!$1:$1048576, 20, FALSE) < RunMatrix!$B4, IF(VLOOKUP(C$1, PasteSheet!$1:$1048576, 21, FALSE) > RunMatrix!$B4, PasteSheet!$Q2, ""), "")

turn into this in the next column D4:

=IF(VLOOKUP(D$1, PasteSheet!$1:$1048576, 20, FALSE) < RunMatrix!$B4, IF(VLOOKUP(C$1, PasteSheet!$1:$1048576, 21, FALSE) > RunMatrix!$B4, PasteSheet!$Q3, ""), "")

then this in the next column E4:

=IF(VLOOKUP(E$1, PasteSheet!$1:$1048576, 20, FALSE) < RunMatrix!$B4, IF(VLOOKUP(C$1, PasteSheet!$1:$1048576, 21, FALSE) > RunMatrix!$B4, PasteSheet!$Q4, ""), "")

Basically, the problem I am having is being able to have the last command --, PasteSheet!$Q2, ""), "") change to PasteSheet!$Q3, ""), "") etc. as I autofill across columns.

Currently, when I autofill across the columns, the -- PasteSheet!$Q2, ""), "") just maintains $Q2 instead of swithcing to $Q3 then $Q4 etc.

Should I incorporate an indirect command?

Thanks in advance for any help.