Simulating Nios II in MODELSIM

I am simulating my Nios II system in Modelsim. It's just a simple hello world project based on an351. I included one more sdram and hello world would be running out from sdram. I am driving my Nios II at 100 MHz, sdram at 100MHz and jtag uart at 50 MHz. I have a clock crossing bridge between them. But my expected output is not observed. Are both Nios II and jtag uart need to be driven by same freq? Thank you.