OK that driving circuit is plain wrong. The first device (for which you've used an NPN symbol, not an n-channel FET) is in source-follower mode - this is no good at all, it won't pull up the second devices gate more than a volt or two.
The first device must be a common-source stage, with a drain load resistor to the +12V rail (something like 1k perhaps). This will level convert from 5V to 12V (and invert the logic). This can then drive the second devices gate at suitable levels to actually turn it on.
