I have a FofmField control on my custom site, nothing fancy:
<SharePoint:FormField runat="server" ID="formField" DisableInputFieldLabel="False" FieldName="Comments" ControlMode="Edit" />
If i set ItemId there in the FormField tag - everything works fine. If i set in Page_Load, the control behaves like it didn't have this property set - displays the description of this field. What am I missing here?