The AsyncTask does not work as expected

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http://stackoverflow.com – In my android application, there is a app file at the sd card, and the same in our server, but the data in the server may be updated. So I make an activity to check if latest data is avaiable. This is an example, there is only one button "Check", when user hit this button, I will get the information of the local data, and then reqest to the server to check if it can be udpated.(THis is done by the CheckTask and a progress dialog will show up during the checking). Then if a update is requred, I will provide a Dialog to tell the user, they can choose "Download Now" or "Download Later", if the (HowTos)