If asinzen has been disabled as a developer in your Seller Central you will have to enable asinzen and add the new MWS Auth Token amazon Seller Central generates into your asinzen Portal.
To accomplish this follow the steps below:
1. Login into Amazon Seller Central and click on this link https://sellercentral.amazon.com/apps/manage
2. Locate the row with asinzen and look under the column click Enable.
3. Here you will be presented with a that tells you are adding asinzen as a developer. Click next.
4. On the next screen click in the checkbox that says "I understand..." and then click next once again.
5. You will then be presented with a final screen showing your sellerID and MWS token. Copy the MWS token into your clipboard.
6. Login into the asinzen web portal click on Manage MarketPlaces
7. Locate your SellerID and paste the MWS Auth Token In the field next to it. Click Save.