Why isn't "Rockhound" a Gold Trophy? [inFamous]

[kitler53]

perpride said:
Just finally got the platinum trophy!!! thought I'd share lol.

i'm soo close.  just need to finish 3 more stunts.  any advice on how to get the stunt where you blast 3 people off a roof? it's hard enough to find 3 people on a roof and when i do it's hard to herd them into one spot.