Connect?ng Humminbird Fishfinder with Lowrance LVR 250 for GPRS signal

Dear Forum!

I would like to connect the Humminbird 587ci HD Internal GPS Combo with the Humminbird 7000301 AS HHGPS Bare Wire GPS/NMEA Connection Cable to my Lowrance LVR 250 VHF Radio. I connected NMEA - and NMEA + of both and activated NMEA out on the Humminbird. I still do not receice a GPS signal on my VHF Radio. I kindly ask for your instructions and remain

with best regards