Highlighting Cells Based On Several Conditions Using VB?

I am writing a data validation macro which checks various conditions and highlights cells if they are incorrect.

i.e. If cell in column D = "specific text", then cell in column AH of the same row must = "specific number". If it is not that number, colour the cell red. If another cell in column D = "another specifci text", then cell in column AH of the same row must = "specific number". If it is not that number, colour the cell red.

What I've found is that I can get one condition of this nature to work, but if I run two or more in the one macro, that they supercede eachother (and thus the final one is the only one that works).

See below sample code.

Code:
Dim val As Integer
val = UsedRange.Rows.Count
For i = 2 To val Step 1

[Code]...