Installation fails with Mac and CUDA 4.0 Toolkit

I am trying CUDA 4.0 into my Macbook Air but it fails.

The driver is installed successfully but the problem is installation of CUDA Toolkit.
it fails and just says “Installation failed.” With this unkind message, I cannot figure our what is wrong.

Is there any idea about what is wrong?
Or, is there any log file I should check?

Regards,
Kimi Kato

I fixed it by myself.
by checking the file /var/log/install.log, I found it failed in unpacking the pkg file.
I download it again and now it works. It was because of broken file.