passing 2-dim float array from COM to .Net

[Lisa]

Hi all,
I have this definition in the .tlb file:
[in, size_is(4, theDataLength)] float** theRawData,
[in, out, size_is(4, theDataLength)] float** theFilteredData,
I was trying to put definition like this in the .il file:
[in] float64[,] marshal([]) theRawData,
[in][out] float64[,] marshal([]) theFilteredData,
It compiles and runs, but when the COM object code is reaching this
line:
float a = theRawData[0][0];
it throws the System.NullReferenceException
How should I define 2-dimentional array of floats so it can be passed
as a method's parameter?
Thanks for your help,
Lisa.