From code behind assign set label text having issues

I have almost 50 labels which i need to set values based on session value validation, here i am doing a simple one but not working.
There is a label control in my form lblProgram, i do see text property.  coould you please tell me what do i need to do, before setting label text values, have almost 50 labels on form.
private void PopulateLabels() { lblProgram.text = "Program No.";
}
 
Thanks a lot for the helpful info.