大侠们，请伸出援手!!!

为什么点击button1后不执行check_send()函数
<%
button1="<input type=""button"" name=""btfs"" value=""发送"" class=""btxx"" onclick=""javascript:return check_send();"">"

response.write "<table border=0 width=100% HEIGHT=22 background='../IMAGES/MAIN_UI/TDHEAD_BACK1.GIF' bordercolor='#F58220' cellspacing=0 cellpadding=0 class='TBH1'>"

response.write "<table><tr><td align=right width='100%' height='22' valign='bottom'> " & button1 & " " & button2 & " " & button3 & "" & button4 & "</td></tr></table>"
%>
而将上面第一句改为:
button1="<input type=""button"" name=""btfs"" value=""发送"" class=""btxx"" onclick=""javascript:document.write('验证发送')"">"
却能执行点击button1后的代码。