Diagnosis
You have chosen a function that cannot be executed on the item youselected.
Examples:

• The item category does not support this function.

For example, you want to display the detail screen for variable-sizeitem data. However, the item you selected is not a variable-size item.

• You want to process sub-items for the item you selected. However, no
sub-items are maintained for the item.

Procedure
Check which item you selected and choose a different function ifrequired.