I'm kinda sad but i hope I can gain trust but im still learning on how to gain it.
I wouldn't worry about it, your trust rating isn't showing as red so people don't know what your trust is unless they actually click into it and want to research it. Most business opportunities will not hold be held back from you.
As for trying to get it fixed, the only way to do so is to talk to the person who left the negative feedback and ask them, make a plea to them to remove the trust. They are the only person who can. The mods here won't get involved...they don't care.
Trust is misused often, it's a flawed system. People use trust as a weapon. Try to avoid dealing independent transactions with people here because you always the risk that someone leaves you a bullshit negative trust, simply because you've created competition for them.
