My wife is at the house, and I'm at the office, or so I believe she is. The truth of the matter is that either she is at the house or she isn't. Suppose I don't know either way. In no way does my knowledge (or lack thereof) alter the the truth of the matter. If I say that she's at the house, then what I say is true if (and only if) she is in fact at the house. Neither belief, knowledge, nor wishes upon a star impact the truth of the matter.
Also, knowledge implies truth whereas truth does not imply knowledge. Additionally, knowledge implies belief whereas belief doesn't imply knowledge. If I know something, then I believe something, but just because I believe something, that doesn't mean that I know something. If I believe something, I do not therefore know something, furthermore, if I believe something, then what I believe is not therefore true. If I know something, then not only do I believe something, but what I believe is true--not because I believe it but because we cannot know something to be true unless that something is true.
A belief is not therefore an unjustified belief merely because a belief is false. If my wife has always been at the house at this time, and if she tells me she's at the house, and if my child says she's home with her, and if there's no history of deceit, then I have justification for holding the belief I do. If it turns out that my belief is false, my belief was not therefore unjustified, as the truth of the matter isn't what's pertinent to whether a belief is justified or not.