were you lunging on a line or in a pen?
When a horse is "blowing you off", as my teacher would say, she would tell me to "fall apart!". That meant to move around, flap your arms, or flail the rope or smack the ground or flip the flag around, or whatever it takes (look like a crazy woman) to make the horse wake up and think that you have something imortant to say. That's what I would say to you; Fall apart. If you said go, GO and GO!! And he is eating grass, then . . Fall apart!
The other horse, in the stall , practice getting it to turn toward you. If it turns its' back on you, make enough of a disturbance that it will turn around to see what's going on. Stop all stiumulae. If he turns away, up the commotion. It can be as little as scuffling the ground, or kicking the stall walls, or snapping a small crop against your thigh. Whatever. When horse looks away, you start the interrruption. After doing it big a few times, I bet all you have to do is rais yoiu hand , or whatever warning gesture and he'll stop turning away from you by the warning alone.