If you specify any of the following fields in the Graph contents section of a chart's settings, you will only be able to select Table under Chart type.

• Date​
• Time fields
• Date and time
• Created datetime​
• Updated datetime​
• Calculated​
  If one of the following is selected as the display format:
  • Date & time (Aug 06, 2012 2:03 PM)
  • Date (Aug 06, 2012)
  • Time (2:03 PM)
  • Hours & minutes (29 hours 47 minutes)
  • Days & hours & minutes (1 day 5 hours 47 minutes)

If you want to display your aggregated data in a chart of another type, consider using one of the workarounds described below.

• Export the aggregated data in table format to a file. Then, import the file data into the Number field of a new app and convert the data into a chart other than a table.
  Make any necessary changes to the exported file before importing it.
  Exporting an aggregate result to a file
  Creating apps from Excel files
  Creating apps from CSV files
• Export the aggregated data in table format or the record data to a file, then use a different tool (e.g. Excel) to create a chart of your choice.
  Exporting data to a file