Error: System.IndexOutOfRangeException

I am using Lunchbox Export Write component, and started creating the heading.

It works just fine, until the sixth value is added to the "Heading" list.

Then it generates the following error message:

System.IndexOutOfRangeException: Collection index must be in the range 1 to the size of the collection.
   at Microsoft.VisualBasic.Collection.IndexCheck(Int32 Index)
   at Microsoft.VisualBasic.Collection.get_Item(Int32 Index)
   at LunchBox.WF_ExcelWrite.SolveInstance(IGH_DataAccess DA)

It is interesting that if you delete the sixth value from the "Heading" list (in this case, delete the "f") the component starts working normally.

Why does this problem emerge?

I am using Grasshopper 0.9.0014, Rhino 4 SR8.

In the Lunchbox.gha right-click Properties, there stands that it is the 0.3.1.0 Lunchbox version.

Thank you for the reply.