a question about jquery xpath return value,can you tell me?

a question about jquery xpath return value,can you tell me?

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<DIV><FONT face=Verdana><FONT size=2><SPAN id=_FoxCURSOR>hi
friends</SPAN></FONT></FONT></DIV>
<DIV><FONT face=Verdana><FONT size=2><SPAN></SPAN></FONT></FONT> </DIV>
<DIV><FONT face=Verdana><FONT size=2><SPAN><input id="chkVideo"
class="chkvideoclass" type="checkbox" operationotate="3" iswrited="True"
videoid="54771"/>---i have checked it </SPAN></FONT></FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Verdana><FONT size=2><SPAN>i used these
code<BR>$(".chkvideoclass:input[@checked='1'][@operationotate<1]").length=1 -
i don't know why i get this result,i think it's must be return
0</SPAN></FONT></FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Verdana><FONT
size=2><SPAN>$(".chkvideoclass:input[@checked='1'][@operationotate!='3']").length=0
- it's ture</SPAN></FONT></FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Verdana><FONT size=2><SPAN><BR>who can tell me ,thx very
much</SPAN></FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV align=left><FONT size=2>
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</FONT></DIV>
<DIV><FONT color=#c0c0c0><FONT size=2>fj_frs</FONT></DIV>
<DIV><FONT size=2>2008-01-18</FONT></FONT></DIV></FONT>