Please verify that your date/time info is accurate.
(Device's Settings --> Date & Time)
Please verify that the manually entered time zone is correct; if it is not, uncheck the auto time zone, adjust to the timezone, and re-check the 'auto time zone' option. Please go back to Device's Settings Menu --> Application Manager --> TweetCaster --> Clear Data
Then delete/re-install the application. (This will re-initialize the connection with Twitter's API).