The Quartus® II Software versions 7.2 SP2 and earlier may not generate sub error messages to explain the root causes of a no-fit error, when it is generated during the I/O Analysis phase of the Fitter.
The Fitter should report information such as the following:
Extra Info: Can’t globally route 1 more signal(s) into a region – 9 global signals have been allocated to the region but the hardware only allows 9 global signals
There can be many causes for no-fits. Altera recommends that you check all design guidelines with regard to I/O assignments and clock / PLL usage. If you encounter problems debugging the cause of a no-fit error, you can contact Altera Technical support by submitting a service request via MySupport on www.Altera.com
The problem of debugging messages not being reported is scheduled to be fixed in the next release of the Quartus II software.