curve fit for 4 variables, error 'not enough input arguments'

function [fitresult, gof] = createFit(CO2NonWorkZone, diveIRI, CO2WorkZone,diffeIRI)

[xData, yData, zData, gData] = prepareData( CO2NonWorkZone, diveIRI, CO2WorkZone, diffeIRI );

ft = fittype( 'a + c*x*g*exp(w*y)', 'independent', {'x', 'y','g'}, 'dependent', 'z' );
opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
opts.Display = 'Off';
opts.StartPoint = [0.371420685802539 0.0606895470210004 0.376869074010979];

% Fit model to data.
[fitresult, gof] = fit( [xData, yData, gData], zData, ft, opts );

figure( 'Name', 'untitled fit 1' );
h = plot( fitresult, [xData, yData, gData], zData );
legend( h, 'untitled fit 1', 'CO2WorkZone vs. CO2NonWorkZone, diveIRI, diffeIRI', 'Location', 'NorthEast' );

xlabel( 'CO2NonWorkZone' );
ylabel( 'diveIRI' );
zlabel( 'CO2WorkZone' );
glabel( 'diffeIRI' );
grid on

[Geoff Hayes]

Wu - please include the full error message (all text that is in red) so that we can get an idea of which line is generating the error message. Is it the call to createFit? Also, is this function the one from the File Exchange at here?