timing is meet, but function is not right

[odeafeiner]

hi,

I have a design with Quartus tools 6.1. The timing is meet by timing
analysis report. But the function is not right with some modules.
These modules are instanced with same code. (the other module function
is good). Of course the function simulation is passed. The difference
I can see now is the location of these modules.

do you have some experience with this situation? These modules are core
-timing related and are constrained by fitting.

Thanks very much,

 

[bansalr]

perform timing simulation and see where and how it is failing.