There can be couple of reasons. Sometimes, it can be down for maintenance resulting you not able to create CDP. You try to google to find out for you since you are not getting very good solution. I found this https://mkr.tools/cdp/cdpID(replacecdpID with your cdp id) to make sure the owner of the cdp is the same address as your Metamask account's address. Last way is to contact the owner to find out what was the technical problem.