Div positioning, My Div Stopped Responding to Left Value Changes Options

[PeterBeepBeep]

CODE

.Navhover {position:absolute; top:180px; margin-left:-1000px _margin-left:-1000px; width:800px; height:60px; z-index:1;}

div.Nav a:hover{
border-top: none;
opacity: 0.0;
filter: alpha(opacity=0);
width: 0px;
height: 0px;
z-index:1;
}

.Nav {position:absolute; top:180px; margin-left:-1000px _margin-left:-1000px; width:800px; height:60px; z-index:1;}

Yeah, So no matter what value I enter, the div just stays the same.

Edit:Never mind this post. I fixed the problem, I just needed to re-type the whole thing, Anyone know why that happens?