same message -

Msg 4104, Level 16, State 1, Line 12

The multi-part identifier "SYS.partitions.INDEX_ID" could not be bound.

Msg 4104, Level 16, State 1, Line 16

The multi-part identifier "SYS.partitions.INDEX_ID" could not be bound.

It is line 16

WHEN SYS.partitions.INDEX_ID < 2 THEN DATA_PAGES ELSE 0 END, 0)) * (SELECT low / 1024 AS VALUE

Not so sure why it could not be bound...