[google-appengine] Server error (500) when I tried to re-enable an app

I've disabled an app from Google's app engine Administration - Application Settings. Now I trid to re-enble it. But the brower returns a server error (500). I trid to request permanenant deletion. Again the same server error occurs. How should I proceed? Thanks. -- You received this

[google-appengine] APP cannot be deleted or re-enabled

One of my APP was disabled previoulsy. Now I want it to be re-ennabled. But when I clicked the Re-Enanable button on the Manage disabled status page. It returned a Server Error (500) response. I tried to request permanent deletion and got the same server error. I tried to recreat a new app and