receiver type *** for instance message is a forward declaration

In my iOS5 app, I have NSObject States class, and trying to init it:

states = [states init];

here is init method in States:

- (id) init
{
    if ((self = [super init]))
    {
        pickedGlasses = 0;
    }

    return self;
}

But there is error in the line states = [states init];

receiver type “States” for instance message is a forward declaration

What does it mean? What am I doing wrong?