MATLAB: Error “Not enough input arguments” for a ode-function

odefun

Hi,
I am writing a progrem with Matlab for the solution of a system of differential equations.
The program is:
% Orto-xylene oxidation in an adiabatic PFR.% ethylbenzene -> Anhydrated-xylene + H2% Water as an inert in the systemglobal y0 F0 deltaHR0 P0 ni n y0(1) = 0.0769; % ethylbenzeney0(2) = 0.; % styreney0(3) = 0.; % hydrogeny0(4) = 0.923; % waterFeed  = 1105.; % F01 + FH2O Feed rate [mol/s]F0 = Feed .* y0; % Inlet feed rate of components [mol/s]Tin = 925.;n = 4.;        % Number of reacting compounddeltaHR0 = 124850.; % heat of reaction at standard conditions[J/mol]P0 = 240000.; % pressure [Pa]W = 25400.; % reactor weight [kg]ni = [-1 1 1 0]; % Stoichiometric matrix% Initial conditions (feed and T0)u0 = F0;u0(n+1) = Tin;wspan = [0 W];[w_adiab,u] = ode15s(dfuns,wspan,u0);conv_adiab = 1 - u(:,1)/F0(1);T = u(:,n+1);%function file dfuns function f = dfuns (w,U)global y0 F0 deltaHR0 P0 ni n y = U(1:n)/sum(U(1:n)); % molar fractionsT = U(n+1);k = 3.46* 10e8.* exp(-10980./T); %Needs to be in Pascal K = 8.2.* 10e11.* exp(-15200./T); %Needs to be in Pascal rm  = k.* (y(1)* P0- (y(2).* y(3).*(P0^2))./ K);f(1:n) = -ni(1:n).* rm;Cp1 = 37.778 + 87.940e-3.* T + 113.436e-5.* T^2; % ethylbenzene Cp4 = 36.540 - 34.827e-3.*T + 11.681e-5.*T^2; % water deltaCp = 0.;deltaHR = deltaHR0;f(n+1) = (1./((F0(1)+F0(4)).* (y(1).* Cp1 + y(4).* Cp4 +y(1).* deltaCp)*...    (1 - U(1)/F0(1)))).*-deltaHR.* rm;f = f'; % transformation to column vector
The error I get is in the function at the line:
 y = U(1:n)/sum(U(1:n)); % molar fractions
and states:
Error: File: catPFR.m Line: 37 Column: 1 Function definitions are not permitted in this context.
I don't really understand this: my function seems to have enough inputs to me. Do you? Can you help me?

[w_adiab,u] = ode15s(@dfuns,wspan,u0);