Screen->isSolid(float,float)? [984]

I've got that function:

bool GForce()
{
	if(!isSolid(Link->X,Link->Y+17))
		return true;
	else
		return false;
}

But doesn't compile

Could not match type signature isSolid(float,float)

Why can't I pass integers? Seems like a bug to me, since in Zscript.txt, it is clearly written that isSolid take integers...

EDIT- Ahaha, I'm stupid, I didn't include Screen in front of isSolid...
But I dunno why the compiler hasn't crashed on isSolid being unidentified.. Whatever.