error in runpf function

[naime ahmadi]

Hello,
I run the below code
[MVAbase, bus, gen, branch, success]=runpf('case14');

and I got this error:

MATPOWER Version 6.0, 16-Dec-2016 -- AC Power Flow (Newton)
Operator '-' is not supported for operands of type 'function_handle'.

Error in newtonpf (line 52)
mis = V .* conj(Ybus * V) - Sbus;  % Sbus(Vm)

Error in runpf (line 204)
                [V, success, iterations] = newtonpf(Ybus, Sbus, V0, ref,
                pv, pq, mpopt);

Error in Example_2 (line 72)
[MVAbase, bus, gen, branch, success]=runpf('case14');

I do not know how to fix this.
Thank you,
Naime