can't connect to ams server

I installed avast and adnm with msde and ams maintainance can connect to the database (test connection). Supplying the same user and PW i cant’ logon the server (the server is found and is pingable but looks like machine.subdomain.domain wheras in ams maintainance it says Netbios_name_of_machine\avast while Netbios_name_of_machine is pingable).

The errormessage i get is: “unknown error - unable login in as sa or connection error” (changing servername to something different gives a connection failure, changing PW and/or user to a wrong one does not change the error massage)

License is demo and the installation source is 10 days old (version 4.7)

what can i do??

Thanks for your help
Jan