Failed upload iOS App IPA ad hoc on the devices.

Hi, I've run an App, and i see it well in the iOS simulator.

But after published the IPA ad hoc, it doesn't install on devices,
it seems run all the passages, I see the icon (without the right image) it in the device,
but clicking it on the device it change the name in 'install...'

and in iTunes seem it isn't installed
because once an App is installed you can choose 'remove',
instead on it is still 'install'.

otherwise the App Icon isn't seen, also if it is uploaded in the icon panel.

here the link to download two screenshots

http://we.tl/MBltnhDAoV

Hi Paolo,
distribution Ad Hoc was done
with Xcode I've tis error message:

App installation failed
The application does not have a valid signature

The problem was about the App certificates.
I've done new certificates and the problem was solved!
Laura