Inside the form, I declare one button to call the function to pop out another screen using this code below.

Response.Write("<scr" & "ipt language='javascript'>window.open('report1.aspx','_blank', 'menubar=no, resizable=yes, width=1024,height=768, scrollbars=yes, status=no')</scr" & "ipt>")

but after call out, the main screen all the thing will be bigger. or i try to call alert message write as below,

it also will en-large all the thing in main page! why? how to solve this problem?

you should not use response.write to register your scripts.

read this: http://forums.asp.net/thread/1262387.aspx

I finally know how to write the register client script!

Me.ClientScript.RegisterStartupScript(Me.GetType, 0, "<scr" & "ipt language='javascript'>alert('Cannot Empty')</scr" & "ipt>")

 anywhere also thanks to your guide and reply! mbanavige