Are you using Basic syntax or Crystal syntax in your formulas?

This is valid in Basic syntax if BOTH User_Text1 and User_Text2 have values. If User_Text2 might be null, you'll need to do this:

IF isnull({Quote.User_Text1}) then{QuoteMain.CustDescrip}
Else if isnull({Quote.User_Text2}) then
{Quote.User_Text1}
else
{Quote.User_Text1} & " " & {Quote.User_Text2}

You can only concatenate string fields if none of them have a null value.

-Dell