Bad Authentication after changing the permission


I use “Python Twitter Tools” to develop a personal Twitter client. I created am application with read-only permission. I created an access token and the client was able to read my tweets. Then I changed the mode to read-write-with direct message permission. I said the application was in read only mode. I recreated the access token and it has been more than 3 hours but I can’t retrieve any tweets now. It gives Bad Authentication data [Code 215] error. I tried to search for solution but in vain. Can you please point out where I went wrong. Thanks in advance.