How to use transaction groups with easy chart?

or custom data on easy chart?

That is what database pens are for. You select a datasource, table or view within it, and the value and timestamp columns applicable. Optional “Where” clause for the generated SQL.

If you maintain meta-information about your table/column versus tag combinations, the onTagsDropped extension function can be made to mimic the convenience of the Tag Historian.

I’m attempting to utilize the database pens via transaction groups as well. However, when I run diagnostics from within the Edit Pen prompt, I receive an error stating that "The type of column ‘t_stamp’ is not a date. This is the column that is autogenerated by the transaction group. I’ve also tried using current_date_time as well with the same result.
Any insight would be much appreciated!