the problem about simulating nios system on nios ii eds9.1 with modelsim

Hi!

Building the project on nios ii EDS9.1, why can't generate the new memory.dat file using for the modelsim simulation. i have set the project "only modelsim, no hardware",and the memory.dat is the first building file and can't update for all the later buildings.

wishing you can help me!

Thanks!