I have a COM for Excel writting in C# where I have run into a problem

The COM comes with a wizard that helps the user create a array formula.
But when my code tryes to add the string that makes the array formula to a
range a exception is thrown.
Stack trace:
at System.RuntimeType.ForwardCallToInvokeMember(Strin g memberName,
BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData&
msgData)
at Microsoft.Office.Interop.Excel.Range.set_FormulaAr ray(Object )

The code looks like this:
Microsoft.Office.Interop.Excel.Range RangeFunc = Sheet.get_Range(....
RangeFunc.FormulaArray = FunctionName + OutRangeString + ")"; //This line
throws

My problem is that this only happens on one German PC and no other custormer
has this problem + I cannot reproduce it on my PC.

Does anyone know what can be the root of this problem?

Torben