@Philippe:
The thing is there is no mention of the vCenter server in the extension.xml file...Maybe because the plug-in is not installed so there is no link between vcenter and srm server yet...The extension.xml file is attached.
@Drysdale:
I have this behavior from my computer, from the srm server and from the vCenter server...What do you mean by admin@system-domain ? If it is the vCenter super user, I don't have the password. Have to ask my customer for it.
If I don't find the answer, I think the SR will be my last option...
Thanks guys for the help