Scripting problem

[PutraenusAlivius]

void OnEnter()
{
AddEntityCollideCallback("Player", "ScriptArea_1", "activatemonster1", true, 1);
}

void activatemonster1(string &in asParent, string &in asChild, int alState)
{
SetEntityActive("manhunter_1", true);
AddTimer("", RandFloat(5.0f, 20.0), "deactivatemonster1");
}

void deactivatemonster1(string &in asTimer)
{
SetEntityActive("manhunter_1", false);
AddTimer("", RandFloat(60.0f, 120.0), "activatemonster1");
}

You had the wrong callback syntax in the first AddTimer call.