How to use bus signal from simulink as struct in the matlab function block using coder.ceval?

I want to use my external C code in matlab function block of simulink and I got an error message stated below.

Passing incompatible type for argument 1 of external C function 'AC_Guidance' with coder.ceval. Function 'AC Control law/MATLAB Function1' (#157.182.189), line 9, column 30

How can I resolve this problem? Here is my C code.

void MVUS_Guidance(struct Waypoint wpt_cur, struct Waypoint wpt_pas, struct UAV_States states, double* Velocity, double* Altitude, double* Heading, double* Path_error)
{
	double LLA_cur[3];
	double LLA_pass[3];
	double LLA_ac[3];

	LLA_cur[0] = wpt_cur.Latitude;
	LLA_cur[1] = wpt_cur.Longitude;
	LLA_cur[2] = wpt_cur.Altitude;

	LLA_pass[0] = wpt_pas.Latitude;
	LLA_pass[1] = wpt_pas.Longitude;
	LLA_pass[2] = wpt_pas.Altitude;

	LLA_ac[0] = states.GPS_Lat;
	LLA_ac[1] = states.GPS_Lon;
	LLA_ac[2] = states.GPS_Alt;	
    ...
}

and here is my code in the matlab function block.

function [Velocity, Altitude, Heading, Path_error] = MVUS_Guidance(WPT_cur, WPT_pas, States)


Velocity = 0;
Altitude = 0;
Heading = 0;
Path_error = 0;

coder.ceval('MVUS_Guidance', WPT_cur, WPT_pas, States, coder.ref(Velocity), coder.ref(Altitude), coder.ref(Heading), coder.ref(Path_error));
end