Microsoft Dynamics CRM 4自定义实体表单onload事件未触发

We have a problem with the onload event of the form for a custom entity not firing. The form did work correctly for a period but recently has stopped working. Now none of the code in the event is executed when the form is opened - either when creating a new instance of the entity or when opening an existing one. The code does however get executed when the form is previewed. We have a problem with the onload event of the