why doesn't the background color of my camera change

i'm trying to make a day and night cycle in unity. I managed to get the background color of my camera to change from black(Night) to blue(day) slowly in the morning but I try to change it back to black in the afternoon it doesn't work. What am I doing wrong?

 public class GameWorld : MonoBehaviour {
     public float igametime;
     public GameObject moon;
     public GameObject sun;
 public Camera mainCamera;
     public Vector4 SkyColour;
     public int gametimeSpeed;
     
     public void Start()
     {
         sun.light.enabled = false;
         moon.light.enabled = false;
     }
     public void Update()
     {
         igametime = Time.time * gametimeSpeed;
 
         while (igametime > 1440)
             igametime -= 1440;
         
         sun.transform.Rotate( new Vector3(0.2f, 0, 0) * Time.deltaTime * gametimeSpeed);
         moon.transform.Rotate(new Vector3(0.333333f, 0, 0) * Time.deltaTime * gametimeSpeed);
         // Dawn (this works)
         if (igametime > 0 && igametime <= 60)
         {    
             sun.light.enabled = false;
             moon.light.enabled = false;

             SkyColour = new Vector4(0.0105f, 0.0110f, 0.0176f, 0) *igametime;
             mainCamera.backgroundColor = SkyColour;
         }
         // Day
         else if (igametime > 60)
         {
             sun.light.enabled = true;                
             moon.light.enabled = false;
         }
         // Dusk (this dosen't work)
         else if (igametime > 960 && igametime <= 1020)
         {
             sun.light.enabled = false;    
             moon.light.enabled = false;
             
             mainCamera.backgroundColor = new Vector4(0.63f - 0.0105f * (igametime - 960), 0.66f - 0.0110f * (igametime - 960), 
                         1.056f - 0.0176f * (igametime - 960), 1) ;
         }
         // Night
         else if (igametime > 1020 && igametime <= 1440)
         {
             sun.light.enabled = false;    
             moon.light.enabled = true;
            }
         else 
         {
             moon.light.enabled = false;
             sun.light.enabled = false; 
         }