The book Programming MapPoint in .NET has a good long section on using the DisplayDataMap method.. it's very fidgety. If you have just one parameter that is incorrect or was not exactly as expected, it will through that error. But there's no way (I'm aware of) to tell what parameter was messed up. I pull out the Programming MapPoint in .NET book every time I work with DisplayDataMap. The examples are all in C# (slight differences from VB6/VBA syntax).
Eric

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