I have trouble with the mousescroll wheel

go to the input section and make sure there is an axis called Mouse Scrollwheel, if there is one please make sure to use the exact same name, (Probably you are missing a cap ScrollWheel)

Example: public void Update() { CheckWeaponSwitch(); }

 public void CheckWeaponSwitch()
 {
     float mousewheel = Input.GetAxis("mousewheelname");
 
     if(mousewheel > 0)
     {
         //do something
     }
 
      if(mousewheel < 0)
     {
         //do something else
     }
 }