Be sure you have the right version. Sometimes it is better to try an older version. I do not know what Android version you have, but some versions are only compatible with 2.2 or 2.1.
If you install the older version and it works, it is version compatibility.
im having the same problem with the yahoo mail app. Says there's a mandatory update but then fails on the install. I get alerts and can read the new mail if opened from the alert, but cantlaunch the app. Viewsonic gtablet / 1day old.