Could not load type 'xxx

Question

I get this error in the log. Its a custom ribbon button that opens a dialog with a custom application page. I checked the 14 hive and the aspx is there.

So, i dont know what else to check

Medium      Name=Request (GET:http://xxx/workspaces/yyy/Wiki/_layouts/mycompany/MoveWikiPages.aspx?items=%7C2&source=%7B02F2CF4F-4764-41F3-8819-3059620C56FE%7D&IsDlg=1)    b03c3f87-ddc6-4f93-849c-3b838cfdbab4
04/16/2012 13:59:59.76  w3wp.exe (0x0F08)                           0x1568  SharePoint Foundation           Runtime                         tkau    Unexpected  System.Web.HttpException: Could not load type 'MyCompany.WebTemplates.Layouts.MyCompany.MoveWikiPages'.    at System.Web.UI.TemplateParser.GetType(String typeName, Boolean ignoreCase, Boolean throwOnError)     at 

The ribbon button executes this:

 <CommandUIHandler
         Command="OpenMoveDialogBox"
         CommandAction="javascript:              
              var ctx = SP.ClientContext.get_current();
              var items = SP.ListOperation.Selection.getSelectedItems(ctx);
              var myItems = '';
              var k;

              for (k in items)
              {
                myItems += '|' + items[k].id;
              }

              var options = 
              {              
                url: '{SiteUrl}/_layouts/MyCompany/MoveWikiPages.aspx?items=' + myItems + '&amp;source=' + SP.ListOperation.Selection.getSelectedList(),
                tite: 'My Company- Move Pages',
                allowMaximize: false,
                showClose: false,
                autoSize: true,
                //width: 400,
                //height: 400 ,
                dialogReturnValueCallback: Function.createDelegate(null, function (result, returnValue) 
                {
                  if (result == SP.UI.DialogResult.OK) 
                  {
                      if (returnValue == null) 
                      {
                          SP.UI.Notify.addNotification('Operation successful');
                          SP.UI.ModalDialog.RefreshPage(SP.UI.DialogResult.OK);
                      }
                      else 
                      {
                          SP.UI.Notify.addNotification('Operation successful');
                          location.href = returnValue;
                      }
                  }
                })
            };             
            SP.UI.ModalDialog.showModalDialog(options);"
            EnabledScript="javascript:function GetSelectedItems()
            {
                var items = SP.ListOperation.Selection.getSelectedItems();
                for (var i =0; i &lt; items.length; i++)
                {
                        if (items[i].fsObjType == 1)
                             return false;
                }
                return true;
            }
            GetSelectedItems();"/>
      </CommandUIHandlers>

Answer 1

I answer my self.

Actually the problem my colleague was having, is that when he took my functionality, he changed the name of the files to match his needs.

When the filenames were changes, he forgot to change the Inherits attribute of the page in the aspx file.

Hard to find, but that was the problem.