Getting Error with User Defined Function in Simulink

I am trying to implement the transfer function, in the frequency domain labelled f, of a channel using a user defined function. I keep getting an error saying that the directory has a space character and makes these programs to not work. All I have been doing is double clicking on the MATLAB defined user function in Simulink. What should I do?

[Kaustubha Govind]

Could this be a bug? Can you paste a snapshot of the error? Perhaps you should attempt this to MathWorks Technical Support.