jquery xpath question, can you tell me why?

<input id="chkVideo" class="chkvideoclass" type="checkbox"
operationotate="3" iswrited="True" videoid="54771"/>---i have checked
it
i used these code
$(".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
$(".chkvideoclass:input[@checked='1'][@operationotate!='3']").length=0
- it's ture
who can tell me ,thx very much