Adviser will prevent you from performing a 3D analysis when there are problems with the CAD model that cannot be fixed automatically. It will allow you to run a DD analysis in this case, but it is possible that the analysis will not complete, or that you will have convergence problems.
There are many potential causes for the problems with the model. Check your original CAD file for overlapping surfaces and thin holes. If you are importing as an STL, there may be problems in the STL file generation as well.
You may want to consider:
-Autodesk CADdoctor for Moldflow
-Autodesk Design Link
Design Link will allow to import directly to Moldflow using the software that you used to create the model, which is ProEngineer in my case.
CADdoctor will allow you to fix problems with the part geometry before exporting as .udm for Moldfow.