Got iTunes receipt, but can't find the app on my iPad...

Hi. I've got a receipt for Phototransfer App from iTunes but the app doesn't seem to have installed on my iPad. I've been away for a few weeks when I haven't used the iPad, so to be honest I can't remember whether it did install back at the end of June and now it's disappeared, or whether there was some problem from the beginning.

Please advise.

Many thanks, Mark