Aurora 3600 inverter giving "E013" Wrong input setting

[Nicoyes]

Chaps, I've just installed our first Power One Aurora 3600 inverter with two strings (7 & 8 Romag 235's). When I turn everything on the inverter gives an error code 013. The manual has this down as "Wrong input setting". I guess it thinks there should be 1 not 2 strings.

Have been looking around t'interweb but can't see where to change the config. Any help much appreciated!

Cheers

I have just installed a reconditioned unit. I am going to have East and West facing strings. I have only installed one string at present.
I switched on and got that error code. I disconnected AC and DC, removed cover and flipped jumper switch. Now it's perfect, will switch jumper back when I have other string up.