Hi Lourens
If the config is set up on both Prognosis and AACC sides, this Help article is a summary of the connections Prognosis requires.
Product Guides - Prognosis for Contact Center - Avaya Aura Contact Center (AACC) - Configuration - Prognosis Server Configuration
Note that the Application, Agent and Skillsets metrics are a combination of SQL and RTD data. The licensing and scripts metrics are obtained from SQL alone.
Considering this you could start by checking the log file:
Prognosis\Server\Configuration\irAVAYA_CONTACT.log00*
Also:
To verify the SQL connection and credentials, you might use an SQL client like the MS SQL Server Management Studio.
To verify the RTD connection and credentials there is this command line tool:
Prognosis\Server\Configuration>..\iraaccrtdcli.exe
You could then include your findings, screenshots of the status, agents and scripts displays, and an irfax if you need further assistance from support.
HTH