It would help if you gave us the name of the extension.
Now I can only assume that the extension has the wrong file extension. Use the CS6 Extension Manager to change the extension from an MXP to a ZXP and see if that helps.
It would help if you gave us the name of the extension.
Now I can only assume that the extension has the wrong file extension. Use the CS6 Extension Manager to change the extension from an MXP to a ZXP and see if that helps.