[Marricio]

pawn Код:

if(!strcmp("/nuke", cmdtext, true))
{
     new Float: X, Float: Y, Float: Z;
     GetPlayerPos(playerid, X, Y, Z );
     CreateExplosion(X,Y,Z,4,45);
     return 1;
}

You didn't set the variables X Y Z value, so the explosion created at default value 0.0.