How do you open a baseline file in CircuitWorks for a ProStep change file?

I have the original idx file, which was a test for our board layout. This has been opened, built and saved.

I am attempting to open the next version of the idx file and I get a CircuitWorks error: "A ProStep change file cannot be opened unless a baseline file is opened first."

I have saved as a EDMD and Sync with ECAD, and still get the error.

I do not know how to proceed.

Help....

SolidworksCircuitworks