Somehow, your QlikView datamodel requires the dimension to be a keyfield. Try link_SalesDocument as dimension and the bubbles will show up. I can't give you an answer at this moment why other dimension fields don't work.
Ok, I think i figured it out. Because you have multiple longitude and latitude coordinates in most of your dimensions (cities), the expressions to calculate the bubble position based on the latitude and longitude and the zoom values does not result in the right x and y positions. When you for instance use avg() instead of sum() in these expressions the result is better, but I don't know if this creates other problems.. If I have more time I will do some tests.
I use customer name as my dimension and each customer has one longitude and latitude. When I use customer city as dimension I have multiple logitudes and latitudes. The best solution is to place the bubble in the centre of the coordinates by using avg() in the expression.
