Why my objects names are not shown on the chart ? can anyone help me please?

Hello please can any one tell me how to resolve this issue? I have created this web page to show statistics about products sold in each date, but its seems thts not working, it shows me NaN! But If I go on navigator to see source code of the page, I can see my objects names! Im using Java EE, Spring Framework.

this is a screenshot:  

And this is my code : 

And thts what It shows in the " Show source code of the page " on Chrome navigator :

• Topic Participants

• firasregayeg1220

• jtara-jquery