Ndidia optimus problem?

i bought a new laptop. it has nvidia optimus technology. i set all things in the nvidia control panel to use playing crossfire with my external nvidia graphic card and when i start game i see that crossfire dont supported that technology and i get low fps with my internal intel graphic card.
Nvidia Optimus is working well when i play other high requirement games. For example, i can play crysis 2 cool with ultra high setting. But why i cant play crossfire with my nvidia graphic card? do z8games makes something to fix this problem?
thank you.