Many thanks to John Vitelli for identifying a bug in version 1.0 of the HaPi library. The underlying typo caused the assignUserToProject method to fail with a 404 error. This issue has since been resolved and version 1.0.1 is now available which corrects the typo allowing for the method to function as expected.

Version 1.0.1 can be download by visiting the HaPi Downloads Page.