Personal hotspot issue

Hi,

I'm working with an iPhone4 (upgraded to iOs 6.0.1) and an iPad2 wifi (upgraded to iOs 6.0.1).

The problem is that, after the ios6 (6.0.1) upgrade, the personal hotspot application by wifi doesn't work.

I've noted that:

- my iPad WORKS with my wifi home internet connection and with an iPhone4 iOs5 personal hotspot connection...so, the problem should be with my iPhone (with iOs 6.0.1,

- the personal hotspot connection VIA BLUETOOTH from my iPhone4 iOs 6.0.1 WORKS with my iPad.

What can I do?

Thank you all!