hvorfor vil den ikke åbne i mit target ?

<div id="divFoldSub0_0" class="clFoldSub"><a href="#" onclick="subfoldmenu(0,0); return false" class="clSubLinks" onfocus="if(this.blur)this.blur()"><img src="foldoutmenu2_arrow.gif" name="imgFold0Sub0"  alt="" border=0> [choice 0_0]</a><br>
            <div id="divFoldSub0_0_0" class="clFoldSub2">
                <a href="kontakt.asp" target="mainpage.html" class="clSubLinks2" onfocus="if(this.blur)this.blur()">Sub 0_0_0</a><br>
                <a href="#" class="clSubLinks2" onfocus="if(this.blur)this.blur()">Sub 0_0_1</a><br>
                <a href="#" class="clSubLinks2" onfocus="if(this.blur)this.blur()">Sub 0_0_2</a><br>
            </div>