Thanks Trevor
We're still using 7.0, we tried 7.1 but were so annoyed with the file save feature that we went back to 7.0 and haven't had the courage to upgrade again yet.
I did try error checking in 7.0 but an error isn't generated (just seems to ignore it), but I'll try it in a 7.2 (I think I have that installed but don't use it) to see if it's improved