Cannot see Report Graphic in Dashlet

Hi guys,

I’m using SuiteCRM 7.8.1 on Centos 6.8.
I created a Report from Opportunities module fields. Basically 2 fields “Expected Close Date” and “Amount”
Data and Report configured are displayed in “Report” option
When I try to put it into Dashlet, data is presented but nor of the graphs are displayed.
Here I attached my report config.

Hope you can help me.

Thanks in advance.