SRAM cable problem

[JohnnyS]

I have a Trek Domane + road bike. I changed the internal cassette cable for SRAM Force -[ inner and outer] the cable was installed correctly however it wouldnt work - when pressing the gear lever you cannot change up or down the gears !
Eventhough a experienced bike mechanic could not get it work - has anyone had this problem and solution ?

 

[nublar]

Sounds like there is not enough tension or leverage on the cable.