[EO] Run-Time Error: 9 - Subscript out of range

[macht102]

I get the error when I go to run and compile, then i try and log in, I then click debug and the error occurs at

CopyMemory ByVal VarPtr(Npc(n)), ByVal VarPtr(NpcData(0)), NpcSize

the full section is

Private Sub HandleUpdateNpc(ByVal Index As Long, ByRef Data() As Byte, ByVal StartAddr As Long, ByVal ExtraVar As Long)
    Dim n As Long
    Dim Buffer As clsBuffer
    Dim NpcSize As Long
    Dim NpcData() As Byte
    Set Buffer = New clsBuffer
    Buffer.WriteBytes Data()
    n = Buffer.ReadLong
    ' Update the Npc
    NpcSize = LenB(Npc(n))
    ReDim NpcData(NpcSize - 1)
    NpcData = Buffer.ReadBytes(NpcSize)
    CopyMemory ByVal VarPtr(Npc(n)), ByVal VarPtr(NpcData(0)), NpcSize
    Set Buffer = Nothing
End Sub