HasOne relation returns wrong record

So I have the following table structure

Storage Table

Article Table

Stock Table

My relations are defined as the following

class Article extends Model
{
    protected $table = 'article';
    protected $primaryKey = 'A_ID';
    public $timestamps = false;

    public function stock()
    {
        return $this->hasMany('App\Stock','A_ID');
    }
}

class Storage extends Model
{
    protected $table = 'storage';
    protected $primaryKey = 'S_ID';
    public $timestamps = false;

    public function business()
    {
        return $this->belongsTo('App\Business','B_ID');
    }
    public function stock()
    {
        return $this->hasMany('App\Stock','S_ID');
    }
}

class Stock extends Model
{
    protected $table = 'stock';
    protected $primaryKey = 'STO_ID';
    public $timestamps = false;

    public function storage()
    {
        return $this->belongsTo('App\Storage','S_ID');
    }
    public function article()
    {
        return $this->hasOne('App\Article','A_ID');
    }
    public function movement()
    {
        return $this->hasMany('App\StockMovement','STO_ID');
    }
}

My problem is when i select the stock with the STO_ID = 2 and then access the article via $stock->article it returns the record for Metall even though the saved A_ID of 1 is Wood This only occurs to the second stock. The first stock with the id = 1 returns wood