You are right - the diagram you attached looks wrong. As far as I can tell, page 8 of http://www.tlc-direct.co.uk/Technical/Da...Manual.pdf or page 7 of http://www.gatemotors.co.uk/PDF/EV5_Manual.pdf describes what you have to do (with the coil of the change over relay connected in place of the Yale lock release):
a.1) +12 VDC (+) from keypad power supply unit => COM of keypad
a.2) 0V (-) from keypad power supply unit=> 0V of keypad
b.1) keypad N.O. => 1st contact of relay coil
b.2) keypad 0V => 2nd contact of relay coil
c.1) relay COM to 1st contact of mhouse START
c.2) relay N.O. to 1st contact of mhouse START
a.1) +12 VDC (+) from keypad power supply unit => COM of keypad
a.2) 0V (-) from keypad power supply unit=> 0V of keypad
b.1) keypad N.O. => 1st contact of relay coil
b.2) keypad 0V => 2nd contact of relay coil
c.1) relay COM to 1st contact of mhouse START
c.2) relay N.O. to 1st contact of mhouse START