Time Zone etc

I have a worksheet for Ebay purchases.
Column A is Ebay's ending date & time of sale PST. (07/15/07-22:13:08)
Column B is Ebay's ending date & time of sale EST. (07/16/07-01:13:08)
Column C is my local time ....=now()
My problem is twofold.
Problem 1:
I would like to have column B's date & time be able to automatically add 3 hours to A's PST column. When I try that, I only can get days added. I want the hours only added.
Problem 2:
Column D is a countdown column I have by subtracting C from B. This feature has been working fine, but the last two times I have tried using it, it is now coming up with #value in the Column D cell. I have checked all formatting and I can't see any difference in the rows that worked correctly and the ones that are not working correctly.
Any suggestions?

If A2 is a valid date/time you should be able to add 3 hours with either

=A2+"3:00"

or

=A2+TIME(3,0,0)

but it sounds like you don't have valid date/times if you get a #VALUE! error using =B2-C2

What result do you get if you try =ISNUMBER(B2)? If this gives FALSE then your date/time is possibly text. Are they shown exactly as you posted above, i.e. (07/15/07-22:13:08) are the brackets included, does the cell also contain "PST"?

daddylonglegs,
you hit the nail right on.
I was using a date/time from my custom section of formatting. It was mm/dd/yy-hh/mm/ss.
For whatever reason, it was working well until today and all I could get was the #value thing.
Thanks much for the help. I changed back to a standard date format which seems to be working now.
BTW, to answer your question, no, I was not using the parenthesis or brackets in my formula earlier.