Why is my Table / Spreadsheet in Lt not editable?

The Table and Spreadsheet Panels within Lt exist in both the Basic Category and the Question Category:
A Basic Table or Spreadsheet is a read-only panel as far as the Student Protocol is concerned. These can be used to display example or model results:
servlet.ImageServer?id=015w0000002mPYb&oid=00D20000000HncM
A Question Table or Spreadsheet will allow Students to edit the Table / Spreadsheet in question to tabulate their own values:
servlet.ImageServer?id=015w0000002mPYg&oid=00D20000000HncM
You can easily differentiate between them as a Student: editable Tables / Spreadsheets will have controls beneath them.