SYMPTOM:
'Subscript out of range' error is received when saving a report services document in Strategy Desktop 9.4.1 - 10.x

Subscript out of range
STEPS TO REPRODUCE:
The 'customer' attribute has a grid graph 'dataset 2' defined as a target of a selection.

When 'dataset 2' is removed from the report services document while the above mentioned selector is still defined for 'customer' attribute; 'Subscript out of range' error is received when saving the report services document.

CAUSE:
One possible cause for the error is that an object has been deleted from a report services document that is defined as a target of a selector.
ACTION:
Remove the selector that is targeted to the removed object before removing the object.