How do I get on the roof in Streets of Suburbia?

[die coward]

I can't seem to get on to the roof. I can get on some roofs, but how do I get on the roof at the very beginning?

[die coward]

Ok I finally got the hang of it, but I have another dilema. I still ned 3 more parts and can't find them. Anyone have any idea where they could be?

[die coward]

Ok I finally found every weapon part. When I pressed start, it said there were 0 weapon parts left. Then I finished the level, but no achievement! So I checked the post-game stats and it said I had only collected 81 weapon parts! Do I have to collect them all without dying or something?

[xLCDx]

Then it must have been glitched for you. Just try again.