Peugeot 307 passenger door nor operating from outside

Hi my Peugeot 307 Coupe has a problem with the passenger door not opening from the outside using the handle. This looks like its due to the white plastic piece that the cable a its in and when you pull the handle the white plastic piece pulls the cable to open the door but it keeps popping out and I cannot get itvtonremain in place. I have attempted to strip the interior door panel and can see the white plastic piece bjtvwach time I place the cable into the white plastic piece and close the door and attempt to open the passenger door from the outside the handle comes away from the cable and the door remains closed. I can open the passenger door using the handle on the inside but not from the outside. Any suggestions?? Thanks Stuart