There is a bug with the mondrian.jar in JRubik-0.9.4. This jar fails when there are 2 time dimensions in the same cube. The problem disappears when I use the jar file (with size 2159252) from the mondrian-2.2.1 release. The mondrian.jar distributed with JRubik-0.9.4 has size 2164521
To provoke the bug try this:
Define an OtherTime dimension by copying the code in the Foodmart schema for the Time dimension and changing the name. Then use the dimension as shown next:
<DimensionUsage name="Time" source="Time" foreignKey="time_id"/>
<DimensionUsage name="OtherTime" source="OtherTime" foreignKey="time_id"/>
Try to run a query which uses the cube... You should get an error that complains about 'duplicate alias time_by_day'.
Again, the alternate 2.2.1 jar solves the problem...