why doesnt bottom property works

Heej guys,

so through the forum i found out that if i want a drop-up menu i should change here the top property into a bottom probably with -39px. although when i use bottom, nothing happens, whil now with the top having a negative value the menu crosses my main menu

website : http://www.edwardscholtens.com

#access ul ul {
-moz-box-shadow: 0 3px 3px rgba(0,0,0,0.2);
-webkit-box-shadow: 0 3px 3px rgba(0,0,0,0.2);
box-shadow: 0 3px 3px rgba(0,0,0,0.2);
display: none;
float: left;
margin: 0;
position: absolute;
top:-78px;
left: 0;
width: 188px;
z-index: 99999;
}

p.s. this css is all in my child css 🙂
thank you in advance for helping