Thinkpad W500 - Ad hoc wifi doesn't work with iPad2

[tanhosy]

My Laptop is Lenovo Thinkpad W500 with Intel(R) Wifi Link 5100 AGN adapter.
I created an ad hoc wifi to share internet with my iPad2, but I had problem:
- My iPad2 told that it "connected" to W500 but my ad hoc connection in my W500 show status "Waiting for users"...
- If I connect my W500 with other laptop, it's OK, both laptop show that "connected".
I don't know why, anyone know how to solve this problem. I've try to change some option in my W500 wifi adapter, but it still does'n work.

Thank in advanced.