DLL with insertable object and with OLE Container Control, called in Power
Point work ok. My mistake..

Problem is in Excel..

The reason I am trying it from DLL is that I have 2 add-ins, one for Excel &
one for Power point and I am trying to remove duplicate programming code.
Till now I have same code in both add-ins for chart preview. ex. in Excel, I
have a hidden workbook with a chart, from which I export picture of chart
and I assign it to a picture so user has preview of chart before is created.