Yes, I tried your suggestion and it is fine now.
Thanks for help. :)

>>I have 2 forms. Form1 and Form2.
>>In Form1's Data Environment, I added a table talbeAA. Then I press a button in Form1 which's click event is:
>>thisform.release
>>do form Form2
>>In Form2, its Data Environment has the tableAA too. The form has a button, its click event is:
>>Select Table1
>>Then when I click this button, an error 'Alias tableAA is not found' occured. If I remove tableAA from the Data Environment, this error will be disappeared. How come?
>>The AutocloseTable is True in the DataEnvironment of Form1.
>>Anyone know how to solve this problem?
>
>Your datasession should be private on both form.