Excel 2007 UDF .Net Params

Question

I have a class that Im using for userdefined functions in Excel. The classlibrary is installed and available as an Automation object.

I have no problems creating functions with one or more parameters. And no problems return arrays and 2 dimensional arrays as results.

However Im trying to setup a function that can take variable parameters, but the result always comes back in Excel as #VALUE.

public object TestFunction(params double[] values)
{
     return values.Length;
}

Are params actually possible in functions called by Excel?