I would like to save links to PropertyLinkCollection from code behind.

 PropertyLinkCollection propertyRelatedPages = pageClone.Property["RelatedPages"] as PropertyLinkCollection; // PageProperty

  var linkCollectionClone = propertyRelatedPages.CreateWritableClone() as PropertyLinkCollection;
     

LinkItem item = new LinkItem();
         var pageClone = pd.CreateWritableClone(); // Page to save PropertyLinkCollection to

/* Build the LinkItems here ....*/


linkCollectionClone.SaveData(linkCollectionClone.Value as PropertyDataCollection); // Here is the problem

// In the above line my linkCollectionClone.value  has all values but after casting to PropertyDataCollection the value turns null

                 
//pd.Property["RelatedPages"].Value = linkCollectionClone.Value as PropertyDataCollection;
 //Save Page
                        
DataFactory.Instance.Save(pageClone, EPiServer.DataAccess.SaveAction.Publish);

How can I solve this?