I can't connect to a database file that is in Access 2000 format.

I have service pack 5 installed with MDAC 2.5 SP2 (also tried MDAC 2.6) and
Jet 4 SP 5.

I also get this error if I open the database with Crystal reports. The error
message is: "No a known database type - databasename.mdb"

Can anyone maybe help me with a solution?