Solved,
Virtual dimensions and virtual cubes runs as expected. To solve my issue it is enough to change dimension name:
<Cube name="MyCube" visible="true" cache="true" enabled="true">
<Table name="facts" schema="public">
</Table>
<DimensionUsage source="MyVirtualDim" name="MyVirtualDim Usage 0" <--here!
Should be named: MyVirtualDim
instead MyVirtualDim Usage 0
because is the name of the dimension in the cube.