That's because warp type NPCs can't have a script.
Use a normal NPC with spriteID 45.
prontera,133,183,0 script warp#123 45,2,2,{
if (countitem(7179) < 5)
warp "prt_in",28,169;
else
{
warp "SavePoint",0,0;
dispbottom "You Need 5 Proof of Donation to enter this Warp.";
}
end;
}