Cubes wont Collide

Hello, I am having a little problem with my project I am trying to do. I am trying to have two objects collide with each other and it keeps passing through each other. For example, I two cubes in the scene and when I use the "OnMouseDrag" function to move the cubes, it just passes through each other and wont collide. I tried everything but nothing seems to work. I tried the mesh collider but I dont think I am doing it correctly. My objective is to have the objects (cubes in this case) not to collide. Can anyone please help me identify the problem? Thanks

Here is the code:

function OnTriggerEnter(collision: Collider){

 if(collision.gameObject.tag == "blue"){
     print("blue");

}

function OnMouseDrag(){

 if(collision.gameObject.tag == "blue"){
     print("blue");

}

function OnCollisionEnter(collision: Collision){

 if(collision.relativeVelocity.magnitude > 1)
 {
     print("excellent");
 }