If i have a felony charge that was dismissed why is the army telling me i can not join?

I passed my asvab with a 124 flew through my physical. iv been studing and working out for the past four months. i had a felony charge put on me for theft of property over $500 which was back in 08. it was dismissed though and the recruiter told me theres nothing he can do. so is there any possible way for me to get into the army? iv heard about expunging my record but i dont know if that is the best way to do this.