quartus 7.2 cannot launch the modelsim-altera 6.1g

please

modelsim v 6.1 is installed but not started when i double click on its icon

quartus 7.2 running is ok but i need to work with modelsim(6.1)and quartus (7.2) together and i have window xp also i download a licesing shared the both, i tree the following approch but it was not ok.

- Right click on My Computer icon, click properties

- Select Advanced tab and click on the Environment Variables button (right above OK button)

- in the "User Variables for user_name" section, click new

- Type in LM_LICENSE_FILE in the Variable Name section

- Type in the path (where your license file is located, e.g., c:\altera\license.dat) in the Variable Value section

- Click OK

- Close all the remaining windows by clicking OK in each of them

please help me