Strange error in Quartus 11.0

Hi,

I'm using Quartus 11.0 for synthesis.

I get a strange error when in my project I replace the entity/arch file of one of my sub-blocks for another (with exact same input signals and name) that has very minor differences (registered output instead of latch).

The synthesis proceeeds normally but turns out incomplete when finished (with 0 errors !).

Instead of producing ~5000 logic elements it produces 1000. When I look at the "Resource utilization by entity" tab, I see that some sub-blocks (other than the one whose file I replaced) do not appear and have not been synthesized by the tool.

Any ideas ?

D.