Mi a hiba a kóddal? (C#)

public partial class Form1 : Form

{

int[] Xp = { 12, 112, 212, 312, 412 };

int[] Yp = { 12, 112, 212, 312, 412,512};

int[] Yr = new int[20];

int[] Xr = new int[20];

Random X = new Random();

Random Y = new Random();

Point kep;

int sorszam=0;

int xk, xj,yk, yj = 0;

PictureBox[] kepdoboz = new PictureBox[20];

ImageList[] keplista = new ImageList[10];

int z = 0;

public void KepLerakasX()

{

for (int i = 0; i < 20; i++)

{

sorszam = X.Next(0, 5);

while (xk < xj && Xr[xk] != Xp[sorszam])

{

xk++;

}

if (xk < xj)

{

kep.X = Xp[sorszam];

Xr[xj] = kep.X;

xj++;

}

else KepLerakasX();

kepdoboz[i] = new PictureBox();

kepdoboz[i].Parent = Form1.ActiveForm;

kepdoboz[i].Location=new Point(kep.X,0);

kepdoboz[i].Size=new Size(100,100);

kepdoboz[i].Visible=true;

}

}

public void KepLerakasY()

{

for (int i = 0; i < 20; i++)

{

sorszam = Y.Next(0, 5);

while (yk < yj && Yr[yk] != Yp[sorszam])

{

yk++;

}

if (yk < yj)

{

kep.Y = Yp[sorszam];

Yr[yj] = kep.Y;

yj++;

}

else KepLerakasY();

keplista[i] = new ImageList();

kepdoboz[i].Location = new Point(kep.X, kep.Y);

if (z == 10)

{

z = 0;

}

else z++;

}

}

public Form1()

{

InitializeComponent();

}

private void timer1_Tick(object sender, EventArgs e)

{

}

private void Form1_Load(object sender, EventArgs e)

{

KepLerakasX();

KepLerakasY();

}

private void button1_Click(object sender, EventArgs e)

{

}

}

A futtatásnál ezt a hibát írja ki:

An unhandled exception of type 'System.StackOverflowException' occurred in mscorlib.dll

erre a sorra--->sorszam = X.Next(0, 5);

A kód 20 pictureboxot hozna létre és rakna le elvileg "kisorsolt" koordinátára.