dynamic series chart

I am trying to create a chart with the help of this module https://docs.mendix.com/howto7/extensibility/charts-dynamic-series But i am getting an error saying --Property  Y-axis data attribute  is required. But when i try to add attribute to Y-axis i am not getting an option to insert it. I am using mendix studio pro 9.0.4 Problem i am facing is with step 4.2  6th point  from the above link   Thanks.
1 answers

Hi Ashutosh,

Does the entity which you are selecting have an attribute which can be used as an input for the y-axis? 
By quickly looking at the documentation, it seems as the y-axis should be an attribute of type integer. 
Does your entity have an attribute of type integer?

Hope it helps!