Created a .pkg file in Xcode 4 and cannot run it on my computer

I created a .pkg file of my Mac app using XCode 4. I installed it using the terminal successfully, however when I double click on the .pkg file, I get a message that says, "... can't be installed on this computer".

Any suggestions?

Thanks.

EDIT: This is the error message that I get. I created package by going to Product->Archive. Then in the Organizer I clicked Share->Mac OSX App Store Package(.pkg) and then save the package to the desktop.

This is what's inside the package.

Furthermore, I've inspected the build settings between XCode 3 and 4 is the following

XCode 3

Path to Link Map File 
Debug           build/Alarm Pro.build/Debug/Alarm Pro.build/Alarm Pro-LinkMap--x86_64.txt
Release        build/Alarm Pro.build/Release/Alarm Pro.build/Alarm Pro-LinkMap--i386.txt

XCode 4

Path to Link Map File 
Debug           build/Alarm Pro.build/Debug/Alarm Pro.build/Alarm Pro-LinkMap--x86_64.txt
Release        build/Alarm Pro.build/Release/Alarm Pro.build/Alarm Pro-LinkMap--x86_64.txt

try changing the file extension from .pkg to dmg cause as far as i know all installation files are .dmg and not .pkg

still not working...

well only one thing to change right click the file and select get info

in the open with open....select DiskImageMounter.app and ur good to go... hope this helps...