how to clear data in table

Hi,

I have 3 context nodes.one for sales order number (from VBAK,field vbeln) when I entered sales order number, the data will display in the item table fields (VBAP). I have drop down in item level if I selected drop down value the values will trigger in another table.

when I enter wrong sales order number I want to clear data in both the tables, but when i entered the wrong sales order number the data is cleared in the first table and it still displaying in the second table.

So what i has to do to clear the data in both the tables at the time?

Thanks,

Ashok.