Error about simulating altgx IP

Hello

My English is poor , so I try to express my opinion as clear as possible. I am sorry if I made some syntax errors.

I am learning the architecture of transceivers and how to configure and use altgx IP . About a few days ago , I saw the "High-Speed Serial Protocol Design with Altera Transceiver Devices_Exercise" webcast from altera website and download the exercises.

The exercise is a partially-complete design project without the Stratix® IV GX transceiver block . I need to use altgx IP to complete the project .

I configure the altgx IP as the exercise mannual told me . Now I can compile it but I can't simulate it . When I use modelsim-altera to simulate it .The error is

error: (vsim-3033) d:/modelsim_altera/modelsim_ae/workspace/basic_6g/basic_6g.v(104): instantiation of 'basic_6g_io' failed. the design unit was not found.

basic_6g_io is the instantiation name of the altgx IP .

I have been tried to correct the error for several days. So if you know how to solve it , please tell me. Thank you.