Bug 22934: Add missing use statement

Bug 22934: Add missing use statement

Also fixes a typo

To test:
1 - Add a subscription to a record
2 - Add an additional field in the admin section
3 - Edit the subscription and define the additional field
4 - Ensure you can view the record in the staff client and opac
5 - Without patch ,in the subscription detail page,click the link of the record title. => software error.
6 - Apply the patch. => no error anymore.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Bin Wen <bin.wen@inlibro.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Fixed another typo on L21

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>