Problem finding mines and missing knife

[Idairadahee]

Hello:
The first mine I detected it alright and put the dartboard on it. However, everytime I click with the metal detector on another mine she just steps on it and it blows. There was event a time I got a script error and the game shut down. I don't remember what I did exactly for that.
Also apparently i need to find a knife next to oe of the bodies but it is not there... I can't keep going without it.
Does anyone have a solution?
Thank you.