Bar Chart error when use YearMonth as dimension

[#1]

Hi Guys,

I'm new to qlikSense and try to create first sheet with Barchart. First bar chart with OrderDate and Sum(Quantity) is show but when I try to create another chart by change Orderdate to Auto YearMonth. It show like error as below. If I need to show Sum(Quantity) in Year.Month or YearQuarter, How can I do it?

Order and Order details is separate table join together with orderid.

Please help to guide me to fix this.

[#2]

Problem Solved ... Thank you youtube