I got a lot of problems while installing the Wholesale Prices Module 'dual pricing 138"; After changing all the files to the original program I'm not able to process invoices or packing slips! I get to following errors:

Fatal error: Call to undefined function: zen_address_format() in /home/public_html/admin/invoice.php on line 113

Fatal error: Call to undefined function: zen_address_format() in /home/public_html/admin/packingslip.php on line 110

I found that the customer ID # is coming with the following text:
TEXT_INFO_ADDRESS_BOOK_COUNT1

Any clue How to fix this?