如何才能正确获取信号值

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下面代码执行后，出现VarPtr(value(0))下标越界。
怎样调用 BLC_getSignalValue获取信号值

Private Declare PtrSafe Function iBLC_getSignalValue _
    Lib "BabyLIN64.dll" Alias "BLC_getSignalValue" ( _
        ByVal handle As LongPtr, _
        ByVal signalNr As Long, _
        ByVal P_value As LongPtr) As Long

Public Function BLC_getSignalValue( _
    ByVal handle As LongPtr, _
    ByVal signalNr As Long, _
    ByRef value() As Long) As Long
    Dim rv As Long
rv = iBLC_getSignalValue(handle, signalNr, ByVal VarPtr(value(0)))
    ' swap high and low -> little-endian
    Call Swap_Long(value)
    BLC_getSignalValue = rv
End Function

Sub a()
Dim MyRead As Long, MyVa() As Long
res = BabyLIN.BLC_getSignalValue(linChannelHandle, MyRead, MyVal)

End Sub