How do I solve 'Not enough input arguments'

This is my code for solving the fick's equation. I am unsure as to what is my mistake. Any help is appreciated.

m=1;
xspan=linspace(0,30,300);
tspan=linspace(0,10,100);

sol=pdepe(m,pdefun,pdeinc,pdebound,xspan,tspan);
surf(xspan,tspan,u);

function [c,f,s]=pdefun(x,t,u,dudx)
c=1;
f=(0.02).* dudx ;
s=1;
end

function [uo]=pdeinc(~)
uo=1;
end

function [pl,ql,pr,qr] = pdebound(~,~,~,~,~)
pl=0;
ql=1;
pr=0;
qr=0;
end

I am getting the following error

Not enough input arguments.

Error in partialtrial>pdefun (line 14)
f=(0.02).* dudx ;

Error in partialtrial (line 9)
sol=pdepe(m,pdefun,pdeinc,pdebound,xspan,tspan);

Answer 1

[Walter Roberson]

sol=pdepe(m,@pdefun,@pdeinc,@pdebound,xspan,tspan);

[Khili Khamesra]

Now I am receiving this error-

Error using pdepe (line 293) Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative.

Error in partialtrial (line 9) sol=pdepe(m,@pdefun,@pdeinc,@pdebound,xspan,tspan);

the equation is clearly parabolic, what can be my mistake?