IOS .ipa file Cannot be installed

Hi ,

   I have created an IOS App and   generate the .ipa file via publish  using "distribution provisioning".     But when I try to install the .ipa file with iTune on a iPAD it always shows "installing" and nothing happens.

  But when generate .ipa using BUILD  with "Ad Hoc provisioning"  it can be installed.

   Any reason why the .ipa generated for distribution not work ?

B'rgds

Felix