Texture doesn't show up on the Rift

Since I just want a static GUI (no interaction) to pop up whenever I come close to an object, I work with textures.

Here I have this javascript that works well on non-VR projects:

#pragma strict

private var guiShow : boolean = false;

var riddle : Texture;

function OnTriggerStay (Col : Collider)
{
	if(Col.tag == "Player")
	{
		guiShow = true;
	}
}

function OnTriggerExit (Col : Collider)
{
	if(Col.tag == "Player")
	{
		guiShow = false;
	}
}

function OnGUI()
{
	if(guiShow == true)
	{
		GUI.DrawTexture(Rect(Screen.width/4, Screen.height/4, 1000,500),riddle);
	}
}

It basically shows or hides the texture when colliding with an invisible cube. Working perfectly on projects that use a normal camera.

What changes should I make so that the Rift displays this texture? I don't understand why it doesn't show up because it's not even a real GUI o.o