fx 4800 lion can't install driver

i downloaded the recent driver from the web site and i can’t install it on lion. when i try to install it it says “no driver update is needed for this system. this system already has drivers which support this nvidia graphic solution.”
i have a 2009 8 core macpro


Did you dl the CUDA driver DMG, named [b]devdriver_4.0.31.dmg [/b devdriver_4.0.31_macos.dmg (ORIG. NVIDIA LINK)]with the CUDADriver.pkg inside or trued to use the CUDA prefpane for update?
Using the .pkg should work because it has only an OS Version check (checks if OS X > 10.6.7). For me it worked to install it in LION (as the last CUDA version before).