Getting the number of listbox items in another form

[Lucy]

I have two forms. Form1 with a listbox (with 3 items) and a button. When this button is clicked form2 should open. On Form2 there is a tabcontrol with 4 tabpages. When Form2 loads I want it to show with just 3 tab pages. So on Form1 i have the following variable defined: public int countItems { get { return listBox1.Items.Count; } } On form2 I have made form1 public ( public Form1 frm1; ) and in the form2 load event i have the following: if (frm1.countItems == 3) { tabControl1.TabPages.Remove(tabPage4); } This complies with no errors but when the application is run and the button is clicked to bring up form2, the following error appeas for the line if (frm1.countItems == 3): Additional information: Object reference not set to an instance of an object. Can anyone tell me where I am going wrong? Lucy

[JoeSharp]

hi set the count-value in the form2 constructor e.g. Form2 form2 = new Form2(listBox1.Items.Count); form2.Show(); in the constructor of form2 remove your tabpage. regards