I am unable to deploy OTA iPhone apps via my webserver but services like Diawi can install the app on my device just fine

I have built an iPhone application in Xcode and have generated all of the required certificates and provisioning profiles on Apple's developer website. I have installed the certificates on my computer and the test phone I am using has my OTA distribution profile installed on it.

I have built and exported the application using my distribution profile and certificates and put the xml/plist and ipa files on an SSL secured web server and whenever I try to download the app, it asks if I want to install it and then the installation immediately fails and it tells me the app could not be downloaded. However, I have uploaded the ipa file to Diawi.com and using their website I can install the same app on the phone without any issues.

I do not want to have to rely on a 3rd party service for hosting my application.

Things to check:

1. Make sure your devices UDID is part of the AdHoc provisioning profile you are using
2. Make sure you are signing the archive with this profile
3. Make sure the manifest is correct, all URLs (especially any references to images)
4. Make sure your web-server is setup to recognize .ipa and .plist as the proper MIME types (this has got me a couple of times)