Hi,
Unfortunately, creating a field on all the different types of activities does not mean that it will be available on the activity entity. The activity entity itself does not allow creation of custom fields.
I'm afraid that there is no way to show a custom field on a chart for the activity entity.
What you could do is either create charts on the individual activity types (email, task, etc) in CRM OR create a chart on a SSRS report in which you could union the different activity types together to return the value of the custom field.
Michael Palmer
xRMPalmer
@MJFPalmer
Rockstar365