Problem in passing of Quartus II for ModelSim

[Altera_Forum]

I'm working with Quartus II and I downloaded a example about FFT in Altera's site (http://www.altera.com/support/examples/verilog/ver-cascaded-fft-ifft.html) and i have problem with simulation in ModelSim because file "fft72.vo" is generate in the step Quartus compilation. This situation cause the following error: **error: (vlog-7) failed the open design unit file ''fft72.vo'' in read mode. I believe that this archive belongs to the FFT MegaCore, but I am not right this therefore not it meeting in the directory: C:\altera\72\ip\fft\lib. 

I'm following the README and I have doubt in step 3 where it says: " select "edit an existing custom megafunction variation" and choose the fft intellectual property (ip) block:  ..\ifft_fft_unitygain\bft_unitygain.v ".  The file that I have choice is bft_unitygain.v and select fft v7.2 in "megafunction name", is not? If not, which?  Help me please!!! Thanks!!!

[Altera_Forum]

I have got the similar problem in simulation. My file uses megawizard cores such as RAM, FIFO etc. I got the following error in the modelsim. 

# ** error: (vsim-sdf-3250) top_module_name.sdo(0): failed to find instance '/instance_name'.# error loading design# error: error loading design # pausing macro execution # macro ./top_module_name_run_msim_gate_vhdl.do paused at line 12  Please help me!! Thank you.