Charting: Problems with Months

Dear all, 

I'm quite a novice to filemaker and I'm facing a disturbing problem with the chart feature. 

My goal is to create a database where I record the number of products that I've sent during each month of the last year to the different countries where my customers are based. I've also created a Report, that tells me exactly the quantities per country, with a sub-summary (month) and a sub-total that indicates the monthly quantities shipped. 

The tables are:

- Country

- Orders

   * month_orders (join table of orders)

   * unique_orders (join table of orders)

- Orders Line Item

- Products

 Things are becoming tougher know that I want to add a chart that shows the monthly quantities per country. This means that every time that I try to put on the x axis the month (for instance: the cMonth field based on unique_orders table) the result I get is all the month of every single country and the same happens with the order quantity. So instead of having, for example, 5 bars indicating the quantities shipped in Germany, I have 40 bars, one for country. 

This means that once that I've put on the X axis the month (for instance: the cMonth field based on unique_orders table) and on the Y axis the order, the results I get is a bar chart indicating a value for every single country and a mix of month.  So instead of having, for example, 5 bars indicating the quantities shipped in Germany, I have 40 bars, one for country and a repeating number of months. 

How can I avoid this problem? Thanks for replying. 

Ps. I apologize for my english and  for not having the opportunity to upload a file. 

Michel