OK. I'm stumped. I've got a branch versioned feature service from which I'm trying to create a new version as a child of SDE.Default. Here's are the GP tool parameters:

and here is the error

there is no other version of this name in this database. I don't know if there is an issue with the name provided ('TestVersion') or something else.
Any thoughts or suggestions would be much appreciated.
Thx,
Ed