Syntax error: "fname" cannot run as it appears (Function declaration has no input arguments)

My function is defined as follows:

function [optval, x, y, z] = fname()
... 
end

It is an optimization function that involves importing data, defining constraints and then solving the problem with intlinprog. When I click 'Run', the program runs and generates the intlinprog results

No feasible solution found.

Intlinprog stopped because no point satisfies the constraints.

But the syntax error in the title appears in a message box next to 'Run'. So does this mean my program can actually run as per normal or is there some variable that I am supposed to input? This error did not appear until earlier today.

I can include more of my code if there's a need but it's pretty long and I'm not sure what parts to provide.

Thanks!