Code:
//bmap definition
BMAP* GoshawkChosen = "GoshawkCharacterChosen.bmp";

//Panel definition
PANEL* PlayerOnePan =
{
	bmap = TempBmap;
	pos_x = 20;
	pos_y = 100;
	layer = 8;
	flags = OVERLAY;
}

//last line of this function is the relevant code
function ChooseGoshawk()
{
	ChosenMonIndex = 1;
	ChosenMonster = str_cpy(ChosenMonster, "Goshawk");
	str_cpy(MonsterDetailsString, GoshawkDetailsString);
	str_cpy(MonsterConfigString, GoshawkConfigString);
	str_cpy(CreateRandomButton, "pos_x = 328; pos_y = 450; button=0, 0, RandomButton, RandomButton, RandomButtonBrite, ChooseRandomMon, NULL, NULL; flags |= OVERLAY | SHOW;");
	set(MonsterDetailsText, SHOW);
	set(MonsterConfigText, SHOW);
	PlayerOnePan.bmap = GoshawkChosen;
}

//Then in a different function, I call
set(PlayerOnePan, SHOW);
//but the problem isn't here, it's in the "PlayerOnePan.bmap = GoshawkChosen" line