I need help with Trigger collision detecting tags

So I'm making a (3d) tile swap game (think bejeweled) and I've got a method for detecting rows or columns of 3. Each spot occupied by a tile (in this case, called buttons) also has an invisible gameobject with a trigger box collider. Each button (tile) also has a trigger collider. Both have rigidbodies. I want to have the invisible objects check what tag the object they are colliding with has, then proceed accordingly. Code:

 function OnTriggerEnter(other: Collider) {
     Debug.Log("detected Trigger");
     if (other.tag == "red" ) {
         Debug.Log("1 red detected");
         x += 0.05857;
         if (other.tag == "red") {
             x -= 0.11714;
             if (other.tag != "red") { 
                 x -= 0.05857;
                 y-= 0.05857;
                 if (other.tag == "red") {
                 
 
                 }
 
             }
             if (other.tag == "red") {
                 Debug.Log("3 reds detected");
                 other.tag = "uncolored";
                 
             }
         } 
     }
         
  
     }

I'm getting the message for detecting a collision, but it doesn't know the tag so isn't saying it detected a red.