Both those missions were easy for me, and I had a 90% success rate for the Lance mission (that backstabber. lol spoiler), and 100% for 8ball one. Come on, you must suck if you fail that.
Only GTA mission I have never passed and probably never will: Coffee stand thing with columbians in GTA III.
Oh and your GF progress thing in GTA SA.
*Progress goes down*
"What the forget, I'm in the middle of a god damn mission, that hoe can wait."
*Progress goes down again.*
"Be right there honey!"