Behind Enemy Lines driving me nuts

[crazycelt]

There are three mindfields. you have just go as far you can north and walk your dude down to the roadblock with the mine sweeper. once you detect mines, you have to sweep the whole thing right to left. The guy will make a comment like field is clear.

[Enforcer1213]

How do you know if the guy has detected mines? I can never seem to find them. It's the only secondary objective I can't complete. I can see the guy has the mine sweeper out. do I just move the guy from north to south and that's it?

By the way, I never see engineers putting mines in the road. But I do get the message indicating that I should look for mines when I approach the road and it shows me where to look (red arrows).