Module Loader: "DeployedMetaDataImplementation..." (5.5.4)

[kazuoF]

We have two Sugar CRM installations: One on our live server and one on our test server.

I uninstalled and deleted a package on our live server and tried to replace it with a slightly altered version that I prepared on our test server.

Using the Module Loader, I UPLOAD the package on our live server installation which seems to work. But when I try to INSTALL it, the process stops at 60% and the log says: "DeployedMetaDataImplementation: Modulename (module name) is not a Deployed Module"

What causes this problem and how can I solve it?

[kazuoF]

P.S.: The module appears in "Studio" but not in "Module Loader"