Los serpuclos mission/initiate 2 gang members

Hi, I'm stuck on the Los serpuclos (sp) mission in gta San Andreas where you have intiate 2 gang members to do the mission. I'm doing what it tells me to press on my Xbox 360 controller; RT & left direction button on pad & it won't work. My respect bar is at 10%, I have taken over about 10 hoods/ territories & every time I have passed a mission or killed rival gang members the respect bar still stays the same. This is the only mission I have and it won't unlock other missions until I have completed this one. Please help