Diagnosis
You want to execute a function which requires that one of the sub-lists(the basic list, statistics, or a ranking list) be marked. You can markthe sub-list by placing the cursor on it. The current cursor positiondoes not identify a sub-list, reference a sub-list for which theselected function is not allowed, or identify the totals line ofstatistics.

Procedure
Place the cursor on a line of the required sub-list. Avoid empty lines,headers and the totals lines of statistics.
Check if the function can be used with this sub-list. For example, somefunctions cannot be used with basic lists whose lines have differentstructures (multi-line basic lists).