InfoPath Dev

I'm trying set a field value based on another field plus more information. Can anyone tell me the function used to create this formula? I've tried comcat but it wouldn't allow me to place a number at the end and max wouldn't allow me to use the text.

Example:

WO Field: 1111

PR Field: formula? 

need it to read WO field+text+1 (1111SHT_1) as drop menu is selected it will increase to (1111SHT_2) and so on.

 Well the function is concat, not comcat, but I'm guessing that this was a typo. :)

What are you trying to increment by 1? The number after the "_"? If so, I'd substring the field's value to get that number only and then add one to it. But a lot depends on where you are executing this rule - attach a sample form under the Options tab and I can give you a hand with the formula....

substring(WorkOrder, "SHT14_") + 1 or substring(WorkOrder, "SHT14_", "+1")

The first one gives NaN in the field and the second one stays blank. I don't see the option tab to attach a sample with.