Your provision is going to have a full bundle identifier. For instance, when I work with TappyChicken, it is com.epicgames.TappyChicken which is what was specified when I made the mobile provision I used to sign it. Make sure you have set the value in your Project settings for iOS to the same thing as was specified in the mobile provision.
Go to the Project Settings in the editor. That will pop up a dialog. On the left side, you will need to scroll down until you see the IOS link. Select that, then scroll down a bit until you see the Bundle Identifier. Set that to the value specified in the mobile provision you want to use. There will also be a list of the various provisions and certificates on your computer. Make sure the one you want shows up as valid and has a check mark under the distribution column.
After trying that, send me the updated log from the Output Log window. Make sure it is the whole thing so I can see exactly what it does for each step of the build/package process.
-Pete