Wearied Error

Wearied Error comes Like: BCE0026:'void'cannot be used in boolen context.

Here's the code

 var msg="Make your choice!"; 
 var Background : Texture;
 var RockG : Texture;
 var Rock : Texture;
 var PaperG : Texture;
 var Paper : Texture;
 var ScissorG : Texture;
 var Scissor : Texture;
 var Player : Texture;
 var Computer : Texture;
 
 function OnGUI() {
     GUI.DrawTexture(Rect(0,0,Screen.width,Screen.height), Background);
     
     if (GUI.DrawTexture(Rect(Screen.width/2 - Rock.width * 2,Screen.height/2 + Screen.height/10,Rock.width,Rock.height), Rock))
     {
         
     }
     
     GUI.DrawTexture(Rect(Screen.width/2 - Rock.width + Rock.width/2,Screen.height/2 + Screen.height/10,Rock.width,Rock.height), Paper);
     GUI.DrawTexture(Rect(Screen.width/2 + Rock.width,Screen.height/2 + Screen.height/10,Rock.width,Rock.height), Scissor);

    

On line 15 the error comes

Thanxx in advance