New created SSRS Report Data Provider not showing in Visual Studio Report Designer Dataset Properties

Hi,

I created new SSRS RDP class, then compiled, restart AOS and refresh the cache, but the RDP doesn't show in RDP list in VS Report Designer dataset query properties, SRSReportParameterAttribute(classStr(ContractClass)) and
    SRSReportQueryAttribute('query')  attributes are properly declared also extends SRSReportDataProviderBase in the new RDP class.

Here's the current setup of our environment; we have 2 AOS Service on the Test Inv. and we have many companies in different countries which means multi languages is implemented.

Any idea of what would be the possible reasons that a new created RPD won't show in VS RDP list? 

Thanks,

Ysrael