ASA sub question

[Reffing Rev.]

ASA 10U tourney time...coach dad here...top of the 4th inning I report to home team coach and the pu who is solo and in shorts by the way, and he tells me I can't sub until the bottom of the inning because players have to play defense before they can play offense. Again I've only done nfhs and NCAA and I don't remember s restriction like that, I've done a little u-trip slow pitch with a league rule requiring players to play 3 outs on defense if they bat ...

Is there an ASA rule I'm missing, if so please point me to reference, I haven't found anything. I did check the league/tournament exceptions for this event and nothing was mentioned.