FFT IP core simulation errors

Hello everyone

I've been trying to simulate a FFT IP by modelsim

But I got an error :

** Error: D:/Projects/FFT/FFT/5-11-2012/megafunction wizard test/FFT_WIZ.vhd(34): Library fft_lib not found.

** Error: D:/Projects/FFT/FFT/5-11-2012/megafunction wizard test/FFT_WIZ.vhd(35): (vcom-1136) Unknown identifier "fft_lib".

** Error: D:/Projects/FFT/FFT/5-11-2012/megafunction wizard test/FFT_WIZ.vhd(37): VHDL Compiler exiting

But when I tried to add the fft library which existed in the quartus ip libraries' directory ,it gave me the following error:

# ** Error: (vcom-19) Failed to access library 'C:/altera/90sp2/ip/altera/fft/lib' at "C:/altera/90sp2/ip/altera/fft/lib".# No such file or directory. (errno = ENOENT)# C:/altera/12.0/modelsim_ase/win32aloem/vcom failed.

can anyone advise me what should I do to simulate this IP please.