about license for ModelSim

I have applied for a license from "www.altera.com"and specified the system variable,but when I ran the file diagnose.exe,follow information appears:

"ModelSim ALTERA VHDL Simulator license (alteramtivsim)

The hostid of the license does not match the hostid for this machine.

One of the following is likely:

-The license is intended for another machine.

-A dongle is not plugged into this machine.

-The dongle driver is not installed or is not functioning properly.

-The hostid mechanism has been changed or removed from this machine."

who can tell me how to solve it?