alpha method to fade in UI-elements

Hello everyone! I recently started learning C# and I'm currently trying to put together a little project for the first time. All works well so far, except for the change of the Alpha.

I have a panel of images, and depending on if the mouse hovers over the image, leaves it, or clicks it, the Alpha of the image should change. And it does! however, it only changes from the original Alpha 50 to Alpha 255. It does this from a simple hover, even though I've set hovering to only increase to 100. My debugs work fine, unity understands where the mouse is and what it does, but the alpha only change the first time I hover the image :(

In my Extension method I declare that the Alpha should be set with a float, but I get the error that I can't set my double as a float in the image-script. I'm too novice to understand what's up with that.

Does anyone know where I might have slipped up?

Thanks for any replies :)

The extension method to change Alpha

 public static void SetTransparency(this UnityEngine.UI.Image This_image, float p_transparency)
         {
             if (This_image != null)
             {
                 UnityEngine.Color Myalpha = This_image.color;
                 Myalpha.a = p_transparency;
                 This_image.color = Myalpha;
             }

The image script:

 public class Item_Data : MonoBehaviour, IPointerClickHandler, IPointerEnterHandler, IPointerExitHandler {
     public Item item;
     public int amount;
     private UiSetup UiSet;
 
 
 
     void Start()
     {
         //find the inventory gameobject, and then the inventory script
         UiSet = GameObject.Find("inventory").GetComponent<UiSetup>();
 
     }
 
     //do this when the pointer clicks an item
     public void OnPointerClick (PointerEventData eventData)
     {
         //if the pointer clicks image, alpha will be full
         if (true)
         {
             GetComponent<Image>().SetTransparency(255);
             Debug.Log("clicked");
 
         }
     }
 
     //when mouse hovers
     public void OnPointerEnter(PointerEventData eventData)
     {
         if (true)
         {
             GetComponent<Image>().SetTransparency(100);
             Debug.Log("hover");
         }
         
     }
 
 
     //when mouse stops hovering
     public void OnPointerExit(PointerEventData eventData)
     {
         if (true)
         {
             GetComponent<Image>().SetTransparency(50);
             Debug.Log("leave");
         }
     }
 
    
 }