I am trying to use the noise_table noise function using the module included below. The ac simulation result, connecting the tnoisesourcemin terminal to gnd and the tnoisesourceplus terminal to a simple beam stiffness model, is a zero displacement magnitude output for all frequencies. I am working in Virtuoso 6.1.4.
Does anyone have any suggestions what I'm doing wrong?

Many thanks in advance,
Richard


//Verilog-AMS HDL for .....
`include "constants.vams"
`include "disciplines.vams"

module NoiseTable (tnoisesourceplus,tnoisesourcemin);

   inout tnoisesourceplus,tnoisesourcemin;
   kinematic tnoisesourceplus,tnoisesourcemin;


// mechanical properties    
//    parameter real mag = 0.000001;  // N/m

// noise source amplitude information
parameter real f1 = 0.001; //Hz
parameter real A1 = 0.000001; //m
parameter real f2 = 0.01; //Hz
parameter real A2 = 0.000001; //m
parameter real f3 = 0.1; //Hz
parameter real A3 = 0.000001; //m
parameter real f4 = 1; //Hz
parameter real A4 = 0.0000001; //m
parameter real f5 = 100; //Hz
parameter real A5 = 0.000000001; //m

analog begin

Pos(tnoisesourceplus,tnoisesourcemin) <+ noise_table({f1,A1, f2,A2, f3,A3,f4,A4, f5,A5}, "surface");

end

endmodule