Problem CC and plane

Hello. I have a problem with the movement on the plane to the vertical position. I get controller.isGrounded is false, the animation plays falling and character falls in one place.

 if (controller.isGrounded || fallTimer < 0.5f)
 {
     getHorizontal = Input.GetAxisRaw("Horizontal");
     getVertical = Input.GetAxisRaw("Vertical");
 
     moveDirection = new Vector3(getHorizontal, 0f, getVertical);
     moveDirection = Camera.main.transform.TransformDirection(moveDirection);
     moveDirection.y = 0f;
     moveDirection.Normalize();
     moveDirection *= speed;
 
     if (getVertical != 0.0f || getHorizontal != 0.0f)
     {
         SetState("A_SPRINT");
     }
     else
     {
         SetState("A_IDLE");
     }
 
     if (Input.GetButtonDown("Jump") && fallTimer < 0.2f)
     {
         moveDirection.y = 7f;
         timer = 0.0f;
         SetState("A_STAND_JUMP");
         fallTimer = 0.5f;
     }
 }
 else
 {
     if (fallTimer >= 0.5f && NowState != "A_STAND_JUMP" && NowState != "A_STAND_FALL")
     {
         SetState("A_STAND_FALL");
     }
     if (NowState == "A_STAND_JUMP")
     {
         if (!anim.isPlaying)
         {
             SetState("A_STAND_FALL");
         }
     }
 }
 
 if (!controller.isGrounded)
 {
     fallTimer += Time.deltaTime;
 }
 else
 {
     if (NowState != "A_STAND_JUMP")
     {
         fallTimer = 0f;
     }
 }

How I can get isGrounded true on the plane?