I am trying to create a custom data validation rule that would allow only specific values into the cells. These values can be only quarter decimal numbers, whole numbers, or certain text. I used the OR function and it seemed to work. However, I get the #VALUE! error when I mix values and text. I am wondering if the problem is that although I have version 2010 at home, I am working on a laptop that only has version 2003 of Excel.

Can someone please help me out?

Here is my formula:
=OR(C17-0.75=TRUNC(C17), C17-0.5=TRUNC(C17), C17-0.25=TRUNC(C17), C17=INT(C17), C17="A", C17="G", C17="T", C17="D")

Thanks a million in advance!
JP