R12 invoice approval , AME workflow error

screen shot of error

Hi,

A client of mine encounters error in the AME Invoice approval process. She encounterrs the error ' An Invalid Setup has been detected for the current transaction type in Approval Management. Please contact your System Administrator'

She checked for a wrong setup by running the diagnostics. The diagnostics does not indicate any error.
The attributes are not erroring out either.

The problem is only with invoice approval process in Payables.
There are no issues in Purchasing and HR.

I have created a link for the screen shot . Please suggest what should be done

Thanks
Krithika S