Windows 7 Activation Error

I did a clean installation of Windows 7 on my Dell Inspiron 5520 because my boot time was absurdly long and I assumed there was just something wrong with the installation (this was correct, but irrelevant to this issue).  After I reset the PC and booted up Windows again, I checked the computer's properties, and it said that the product key is not available for activation.  Windows support told me to contact Dell, so I called customer support but my call was disconnected while being transferred between representatives and I don't have the time at the moment to redo the call.  Anyone know the right actions to take in order to get my key fixed?  I don't have warranty anymore, by the way.

Did you use a Dell Windows 7 Reinstallation DVD or a Digital River .iso?

I would advise you to use the activation backup and recovery program and Dell ABR files:

http://dellwindowsreinstallationguide.com/a-clean-install-of-windows-7/microsoft-product-activation/the-activation-backup-and-recovery-program-windows-7-version/

The third video, this will give you the activation mechanism of the Dell Windows 7 Reinstallation DVD.