Dynamic Map - works for a while then return this cross error icon

[#1]

Hi,

I am new to Qlikview.  I was using dynamic map to map some Lat and Long.  It worked for a while. then it returns the following icon error.  Anyone can explain to me the reason? and what do i need to do to resolve the error?

Also, can anyone explain the dimension and expresssions - what are the functions and what fields should i fill them with? 

A third question is that the size of my bubbles are the same... how do i change the size according to the number of data points?

thanks in advance!

[#2]

Qlikida,

1. Can you help me to understand how you are using dynamic map, using an extension obj. or how ?

2. let us assume a case situation that i want to see how many dealer are there in a specific region, so region will be my dimension & count( distinct dealerID) will be my expression. it depends on what you are trying to show in that map.

3. In Expressions tab there is an option for bubble size enable it and give an expression which will size the bubbles based on the value. In the above case i can size my dealer bubble based on no. of trades they made.

thanks

Brad