A common problem might be trying to iterate over Array which has no values in it. For example:
Dim myArray() As Integer For i = 0 To UBound(myArray) 'Will result in a "Subscript Out of Range" error
To avoid this issue, and to check if an Array contains elements, use this oneliner:
If Not Not myArray Then MsgBox UBound(myArray) Else MsgBox "myArray not initialised"