Why can't the Army secure a conviction against Ehren Watada?

Ehren Watada, LT who used his scholarship to West Point to complete his education, turned his back on his Soldiers and refused to deploy with his Stryker BN to Iraq. I want to know why the Army has not convicted him of the charges that he faces? The Army prosecutes and generally secures convictions for enlisted personnel who do the same thing, but by allowing him to ride out his commission igned to a desk at Ft. Lewis aren't the leadership of I Corps condoning his behavior? If they are going to prosecute him, either secure a conviction, or overturn all convictions of enlisted Soldiers for the same offenses of missing movement and refusing to deploy.