The following error is given by ModelSim 10.1b when compiling MIG DDR2:
The ModelSim 10.1c release notes state:
Product Changes in 10.1c:
Release 10.1b introduced a new error, number 2902.
By default in the 10.1x series of releases this should have been a warning.
In future releases this will become a suppressible error.
If you are using ModelSim 10.1c, you can ignore this error and complete compilation.