کسی می تونه کمکم کنه لطفا؟

مشکل این چیه؟

کد :

public class Chain_names
{
public string name;
public int Mols_no;
public class Mol_cl
{
public string name;
public int Atoms_no;
public class Atom_cl
{
public string name, X, Y, Z, XY, YZ;
}
public Atom_cl[] Atomm_cl = new Atom_cl[100];
}
public Mol_cl[] Moll_cl = new Mol_cl[100];
}
public Chain_names[] chainName = new Chain_names[1000];



پیغام خطا:

Object reference not set to an instance of an object.


می خوام اینطوری مقدار بدم:

chainName[0].name = "2RDF";
chainName[0].Mols_no = 200;
chainName[0].Moll_cl[0].name = "ALU";
chainName[0].Moll_cl[0].Atoms_no = 2000;
chainName[0].Moll_cl[0].Atomm_cl[0].name = "T";
chainName[0].Moll_cl[0].Atomm_cl[0].X= "1.02";
chainName[0].Moll_cl[0].Atomm_cl[0].Y = "1.25";
chainName[0].Moll_cl[0].Atomm_cl[0].Z = "2.00";
chainName[0].Moll_cl[0].Atomm_cl[0].XY = "0.75";
chainName[0].Moll_cl[0].Atomm_cl[0].YZ = "1.12";

اما نمی ذاره.