>Thanks Keith, but i didn't understand. (Where should I place form action ??)
>Thanks in advance.
>my code
>asp:button id="btnDownload" visible='< % IIf(DataBinder.Eval(Container.DataItem, "ppcc") = "P", "True", "False")' form action="download.aspx"
>input type="button" value="Download" title="Click" onclick="window.open('download.aspx?posttype=AIR-E&mawbno=< %#DataBinder.Eval(Container.DataItem, "mawbno")% >&hawbno=< %#DataBinder.Eval(Container.DataItem, "hawbno")% >&ppcc=< %#DataBinder.Eval(Container.DataItem, "ppcc")% ','','width=400,height=350,scrollbars=yes')"


Agnes,

I don't understand the code fragment that you posted. It looks like you are opening a new browser window on download.aspx when the button is clicked but you are also posting back to download.aspx (which I assume is a different page than the page where the controls reside). And the button is not a server control yet you have inline server-side script within the button.

If you want to control whether the button is visible (i.e. whether it is included in the HTML), then you have to use a server-side button and set its visible property before .NET renders the HTML or use javascript to set the button.style.display attribute to "none" after the HTML is sent to the browser.