I GOT IT! The textbox name defaulted to LastName and it was causeing it to confussing the field name of LastName. Once i changed the control name i was all set! Thanks for all your help. Sometime you just need to talk things out with someone!

I understand that completely. What doesn't make sense is why is it just these two field names.. The only thing i can think of is that it's getting confused with another field? I even searched all table for ambiguity with no luck! Last i can use these same field names by themselfs with no problem. It's bugging me!...

Yes, it's a textbox control that i'm setting the controlsource to the function I supplied. I am not currently checking for null values but i'm currently using test data that has all fields completed. In the future all these fields will be require when the user is performing dataentry.

I have to say i'm stumped, i've never had this problem before....

I agree. Thats a perfect solution....

This has been driving me nuts for some time now. I have a table that has field names FirstName, LastName, MiddleIntial, AssumedFirst, AssumedMiddle,a nd AssumedLast. But it seems that whenever I concatenate anything with the LastName field or the AssumedFirst I will receive a #error. ANY other combinations will work just fine? I don't get what wrong with these two fields? I have checked there name against the table and everything looks fine. Here's...