Linking main form to Subform

[simpsondm]

I have a problem which I can't figure out I have a mainform that has a subform when opening the subform from the main for I want it to open and show only the cordination records and if I close the subform and change to another record in the mainform then go to the sub form again it only shows the cordination records in the subform. Can someone please help me with this.
Thanks

 

[mas5]

Sounds like you might be missing the link fields. In design view of the main form click on the subform so you got the property sheet. Then in the data tab set your child field and master fields. That should take care of it.