2006 ford f150 oem dvd nav problm

i bought a ford dvd navigation for my f150 and have it all installed with video and power working but no speaker sound is coming out .... can someone give me some help into why this is happening ... thank you

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HELP

          LIGHT GREEN/ VIOLET          (+)          RADIO HARNESS          
     Accesory          LIGHT GREEN/ YELLOW          (+)          RADIO HARNESS          
     Ground          BLACK          (-)          RADIO HARNESS          
     Illumination          LIGHT BLUE/RED          (+)          RADIO HARNESS          
     LF Speaker (+)          ORANGE / LIGHT GREEN          
     LF Speaker (-)          LIGHT BLUE/WHITE          
     RF Speaker (+)          WHITE/ LIGHT GREEN          
     RF Speaker (-)          DARK GREEN/ ORANGE          
     LR Speaker (+)          GRAY/LIGHT BLUE          
     LR Speaker (-)          TAN / YELLOW          
     RR Speaker (+)          ORANGE / RED          
     RR Speaker (-)          BROWN / PINK          
     Steering Cntrls          OPTIONAL          
     Speed Cntrl          YES          
     Radio Security          YES          
           
     Note: makes no representation or warranty with respect to the above information including its accuracy, completeness, or its freedom from third parties' proprietary rights. disclaims all liability or responsibility for errors or omissions therein or any decision made by the recipient in reliance thereon. The installer must verify any circuitry with the proper test equipment prior to installation.      
If it does not work it may have a factory amplifier