DDE method invoked with no channel open
A DDE method (LinkExecute, LinkPoke , LinkRequest , or LinkSend ) was performed on a control that is not involved in a valid DDE conversation.
Changing the LinkTopic property terminates an existing DDE conversation but does not automatically establish a new conversation. After changing the LinkTopic property for a control, you must set the LinkMode property to 1 (Automatic) or 2 (Manual) before executing a DDE method on this control.
You executed a DDE method on a control with LinkMode set to 0 (None). Set the LinkMode to 1 (Automatic) or 2 (Manual) and try again.