If you use PDF invoice rather than the standard invoice or packing slip you will get errors. Missing arguments.
This is because the order editor adds a couple of arguments to the address function in functions - general.php.
These are not needed for the invoice and packing slip but placeholders will need to be added.

open admin - invoice.php and add to lines as detailed

find

tep_address_format(

at the end of this line after the "n") add the following ,'','' before the bracket

mine looks like this when complete

$pdf->MultiCell(70, 3.3, tep_address_format(1, $order->customer, '', '', "n",'',''),0,'L');

Do this as many times as the tep_address_format( line appears 3 in my case

same in admin - packing_slip.php

do this on each occurence of the tep_address_format

Enjoy

Steve



More...