Hi Jally,
The reason that is not showing up on your site is because you are using custom code (under Site HTML -> Top of Page Editor). The cart will not appear at the top when you use your own code. You have two options to get it to appear with your own code.
1) You could change the display option to be Use Both Default and Custom under the Top of Page Editor. If you do this, you would want to make sure that you have images/clear.gif under Site Layout -> Logo Editor. You would also want to make sure that you have nothing under Site Layout -> Top of Page Banner Editor.
2) You could use the <% DRAWCART %> feature. For more information on how to use this, look for the post under 4.0 that is called Tech Spot (Available
here)