Diagnosis
The compiled ranked list does not have a field that can be used as asort field.
Since a ranked list always requires exactly one numerical sort fieldthat has been designated as a ranked list criterion, the ranked listcannot be generated nor saved in this form.

Procedure
Sort the ranked list according to exactly one numerical field (type P,I, or F). If there is no numerical field in the ranked list, add anumerical field and sort according to this field.
If the counter function has been set under Settings -> Statistics, youcan use this field as the criterium, if no alternative field isavailable.