Javascript does NOT work OnChange but works perfectly OnLoad

Hello. My Javascript code works perfectly OnLoad trigger but Only two of the conditions will be successfully satisfied OnChange of a field, leaving out one condition which is to hide a Quick View section and its field. Here is the code:

       function CaseType_OnChange()
  {
      //Get OptionSet CaseType
      var caseType = Xrm.Page.getAttribute("casetypecode");
      if (caseType == null)
      {
          return;
      }
      //Show or Hide Tab and Sections, if CaseType is Claim
      if (caseType.getValue() == 1)
      {
          ShowOrHideTab("tab_1", true);
          ShowOrHideSection("section_1", true);
          ShowOrHideSection("section_2", true);
      }
      else
      {
          ShowOrHideTab("tab_1", false);
          ShowOrHideSection("section_1", false);
          ShowOrHideSection("section_1", false);
      }
  }

  function ShowOrHideTab(tabName, tabVisibility)
  {
      //Get Tab
      var tab = Xrm.Page.ui.tabs.get(tabName);
      //Set Visibility if tab was found
      if (tab != null)
      {
          tab.setVisible(tabVisibility);
      }
  }

  function ShowOrHideSection(sectionName, sectionVisibility)
  {
      //Get Tab
      var section = Xrm.Page.ui.tabs.get("general").sections.get(sectionName);
      //Set Visibility if section was found
      if (section != null)
      {
          section.setVisible(sectionVisibility);
      }
  }

SO, on that ShowOrHideSection("section_1",false), the section of which it is a Quick View form, it is not getting hidden OnChange of the CaseType field.

What could be the problem?

Best Regards

Junior Consultant