[Scenario]

Okay, I whipped this up for you.

pawn Код:

public GateCheck()
{
    if(IsPlayerInRangeOfPoint(playerid,15.0,2220.3957,-1139.3205,25.6949))
    {
        if(IsPlayerAdmin(playerid))
        {
            MoveObject(admingate1, 2227.763428, -1146.743164, 26.401253, 3);
        }
        else
        {
            SendClientMessage(playerid, COLOR_RED, "This gate is for administrators only!");
        }
    }
}

That isn't the full code because I don't know what gate you have defined as "admingate1", so if you supply me the "CreateObject" line for the gate you'd like to open for admins only, I'll complete your code for you...