Kiith

Thanks Guys, Your right it is a auto-enter calculating field, sorry for not including that in my original post. I thought that the IsEmpty was the answer but my understanding of Filemaker it fairly poor, thank you all for your assistance I'm sure what you've suggested will work.

My company recently upgraded from FM4 to 6 at at the same time crossed over to PCs. The transition was relatively painless but I'm still having one problem. It seems that FM4 defined the message in the subject line to mean that no calculation will take place until all field contain a value, while FM6 defines it as the value isn't calculated until one of the referenced fields contains a value. We have 3 fields for this calculation (number) and as soon as one field is referenced the calculation runs and gives a result of zero. If anyone who has come across this can offer any assistance or a suggestion it would be great. Thanks