могу предложить такое решение

'Декларация
Private Declare Function ArrPtr Lib "msvbvm60.dll" Alias "VarPtr" (ptr() As Any) As Long
Private Declare Sub RtlMoveMemory Lib "kernel32" (dst As Any, src As Any, ByVal nBytes&)



'функция проверки
Private Function IsEmptyArray(ByVal ptr As Long) As Boolean
Dim myPtr As Long
RtlMoveMemory myPtr, ByVal ptr, 4
IsEmptyArray = IIf(myPtr = False, True, False)
End Function


'Использование функции
' -1 пусто
'arrTest -массив

Private Function GetUbound() as Long
Dim i As Integer
If Not IsEmptyArray(ArrPtr(arrTest)) Then
i = UBound(arrTest)
Else
i = -1
End If

GetUbound=i
End Function



Erase ArrName - обнуление массива