In src/map/battle.cpp find for: { "max_body_style", &battle_config.max_body_style, 1, 0, SHRT_MAX, },
Change to:
{ "max_body_style", &battle_config.max_body_style, 4, 0, SHRT_MAX, },
Recompile and try again, please
And, what script command are you using to open this dress room?