Radical Gearbox Reverse

I am going through an SR8 I recently aquired and reverse appears to be non functional. It has paddles and I use the lockout lever to get to neutral and try to select reverse from there but there is no engagement of reverse. The indicator says R but it's still in neutral. Also tried manually shifting at the gear box - same thing. 1 through 6 work fine.

Any experience out there on this?

Radical Gearbox Reverse