Problem with changing Access file path!

I have a form using ADO coltrol with a predefined connection string. The Form have one DataGrid Control and a EditText control. Now I want to change connection string of the ADO control to specify right location of data file everytime loading form and the problem occurs.
The code in Form_Load like:

myADO.ConnectString= CnnStr 'point to the location of Access file, this is OK
myADO.RecordSet.Refresh



When running, DataGrid retreives data well, except the (1,1) cell is blank. And Edit Text is blank, too. I dont know what happen. If you know pls help me ASAP, this is very urge.
Thanks
TQSANG