The assign activity is reporting an error, which only shows up in the Project Explorer view (not in the actual editor). The assign is a sample assign between two variables. The error is:

The XPath segment "child::app:Application" cannot be resolved. Test.bpel /Test/bpelContent line 45 BPEL Validation Marker

Although it shows as an error, it actually deploys and runs fine.

Have a sample project attached