Try using this:
function SWATSpawnPointData::onAdd(%a,%b,%c,%d,%e,%f)
{
echo(%a SPC %b SPC %c SPC %d SPC %e SPC %f);
Parent::OnAdd(%this,%obj);
schedule(50,0,"checkSwatSpawn",%b);
}
If there are any other arguments being passed, revise the onAdd method to include them. Also, trying performing a .dump() on each argument to see what exactly it is. .getTransform() can only be performed on valid objects.