Purchase Order Form personalization

Hi,

I want to do the following personalization

- When the Approve button in PO is clicked the Forward check box is to be checked and the value to be  specified for the Approval path.

I have done the customization for checking the Forward to check box.

This has been done in the When New Block instance with processing mode as Both.

The check box value is ticked when I click on the approve button. However the approval path field is not enabled unless I physically uncheck and check the option again.

I cannot therefore provide the value in the approval path.