I keep getting an error on my for loop.

I'm trying to use t$$anonymous$$s code for my for loop to print out the days in the calendar:

 void OnGUI()
 {
     for (i = 0; i < numOfDays + leadDays; i++) 
     {


         if (dates[i].dateOfMonth == 0)
         {
             labelInput = " ";
             GUI.Label(new Rect ( 25, i * 10 ,200,50), labelInput);
         }

         if (dates[i].dateOfMonth >= 1)
         {
             labelInput = dates[i].dateOfMonth.ToString();
             GUI.Label(new Rect ( 25, i * 10 ,200,50), labelInput);
         }
     }
 }

but I keep getting t$$anonymous$$s error:

ArgumentOutOfRangeException: Argument is out of range. Parameter name: index System.Collections.Generic.List`1[Dates].get_Item (Int32 index) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.Collections.Generic/List.cs:633) DatesDatabase.OnGUI () (at Assets/SCRIPTS/DatesDatabase.cs:147)

The code actually works fine but I keep getting t$$anonymous$$s error and I'm worried that it might cause some bug later.