I made some changes to a form and now get the error message

Property setting will not take effect until data environment reloaded (Error 1739)

which has the text

You attempted to set a property on a data environment object (Relation, Cursor) while the
data environment is loaded. The property value will be stored with the object, but the
property will not take effect until the data environment is unloaded and then reloaded.

To unload the data environment 

Issue CloseTables in the form: 
[Formset.]Form.DataEnvironment.CloseTables
To reload the data environment 

Issue OpenTables in the form: 
[Formset.]Form.DataEnvironment.OpenTables

What does it mean and how do I fix it? Help is veryclear on what it means and how to fix it.

Thanks