Calling MATLAB function from C#

Hi all I am trying to call matlab function from my c# project. The function includes wavread function of matlab. The problem is that the .wav file i need to read is to be dynamically created at run time in c#. when i create the file i copy it to the location where matlabfunction_mcr is located in c# project. I also give full path of .wav to matlab function. But when i execute the function I get runtime nullreference exception:

 "Object reference not set to an instance of object"

Can anyone suggest some solution for that?? I'd be thankful.