digi dash speedo

[nova_pipi]

hi all, iv wired in my speedo on my digi dash and it is giving me a reading but it seems to be half of the actual speed that im doing, iv connected the blue red wire from the transducer to the dash but iv used a double wire and connected them both up a while ago, i dont no if this will have anything to do with it, and earthed the brown wire on the transducer, any help would be much appriciated.
thanks
phil

[luke1.4sr]

try flicking the red switch on the top the digi dash in the middle if no help you might have the wrong transducer, brown earth black iginiton live and blue/red signal wire to digi dash