Automating the primary key

[jlc28]

I have been using the code "PWW" & Format([PWWorkorder],"0000000") in order to automate a workorder number. However, because this field is primary key it keeps giving me the error

Index or primary key cannot be null.

It's not throwing the number back into the table. How can I fix this?

Thanks.

 

[jlc28]

Never mind. I got it. Stupid mistake. Thanks