I'm getting this same issue, but mine is on 9.5 (Did not get am:u handle).
EDIT: Nevermind, realized that the problem wa that I was using browserhax. Tried with freakyhax and it works just fine.
Try to use Freakyforms Deluxe. Worked for me.im on steel hax, nfirm downgraded with dsiwarehax and ready to downgrade, it detected the am:u handle the first try but the downgrade failed and softbricked my then 11.0 2ds, emergency mode updated to 11.2, im all preped for the 10.4 to 9.2 downgrade but it still wont detect am:u handle :/
ehh... don't have the money on my account at the moment, cristmas is still 2 weeks away *sighTry to use Freakyforms Deluxe. Worked for me.