Raycast goes (sometimes) through collider

Hi there. I've a annoying problem, where the detection RayCast goes sometimes through walls.

Most times it works how it should, but in the last time i recognize more often this problem (i didnt change the script since a long time, and most times its working correctly).

Following the script i use (JavaScript) and two Screenshots where i caught the renegade Defensetower ("Player" is outside somewhere behind the tunnelwall on a hill, so there are at least two collider between them)... what to do? Its not a funny game when you're getting hit through walls.

 function FixedUpdate(){
 
 for (Entity in IntruderList){

 if (Physics.Raycast(transform.position, (Entity.transform.position - transform.position), Hit)){
 Debug.DrawRay(transform.position, (Entity.transform.position - transform.position) * 30, Color.yellow);
         if (Hit.collider.tag == "Player" || Hit.collider.tag == "Entity"){
             Target = Entity;
             IsSeeingTarget = true;
             IsSearching = false;
             Distance = Hit.distance;
         } else {
             IsSeeingTarget = false;
             IsSearching = true;
             LetsShoot = false;
         }
         }
     }
     
     if (IsSeeingTarget == true){
         
         WarningCycle();
         
     }
 
 }