MATLAB Script which cascaded Transfer Functions

I've tried to use an old MATLAB Script which cascaded Transfer Functions by simply using the multiply character, *, but it doesn't seem to work any more. How should I cascade transfer functions now? This is the error that gets reported; Error using * (line 80) Attempt to execute SCRIPT conv as a function: \\GGBPLF04\xxxxxxxx\MATLAB\conv.m

Error in PinPoint_TF130612 (line 56) TF4=KT*tf([1/W4^2 0 1],[1/W5^2 1/(Q*W5) 1]);% Delta Frequency Notch Filter.