XML-RPC Error (404): after activating Certificates

When i installed and activate Joomdle My Certificates in Joomla then i receive a XML-RPC Error (404): Unknown error
I using joomla 2.5.8 and Joomdle 0.9 version.

This is the only module thats not working, all others works fine.
How can i solve this error?

Do you have the certificates module installed on Moodle?

Yes and when i activate this module i get the XML-RPC Error (404) error.

Are you sure it is this module causing the problem?
I set it up on a local copy, and cannot replicate the error. It seems to be working fine for me (and for some clients using it)

hmmm when i use the site on a normal way without the module everyting works fine
when i enable the module without the login no problem as wel...

when i login as a normal user i get the error message.. only also this error message.
when i eneble the debug function the screen shows this message.

Can it be the PHP settings ?

Can you enable additional debugging in Moodle to see if you get any more info?