How do I refresh Gridview when the page is...

When the page is being refreshed who do I re-bind my gridview data.  I have a parent page with gridview, when the child page closes the parent page gridview needs to be refreshed to reflect the changes.  Can someone help me fix this problem. Thank you:
When the child page closes, refresh the parent and re-bind the gridview so that the new data will appear in the parent page gridview.  
Code behind
protected void Page_Load(object sender, EventArgs e)  {        if (!Page.IsPostBack)        {            bindDepars();            bindGrid();         }     }

error message
Invalid postback or callback argum ...