[julia-users] ccall with callbacks question

[bp2012]

I've been working on calling a c lib from julia. I can open the library and 
basic functions are working fine. However, I am stumped on the ccalls 
making use of callbacks. I've read through the documentation and am just 
not able to spot what I am doing wrong. (Admittedly, my C is very rusty.)

Below are the relevant C header lines from the library:
typedef void * Handle;

typedef enum
{
    Disconnected = 0,
    Connecting = 1,
    Connected = 2,
    Reconnecting = 3,
    Disconnecting = 4,
    SessionLost = 5,
} SessionStatus;

typedef void (*SESSION_STATUS_CALLBACK)(SessionStatus eSessionStatus);
typedef void (*LOGIN_FAILED_CALLBACK)(const char *error);

extern libXC void SessionStatusListener_setSessionStatus(Handle 
listener,SESSION_STATUS_CALLBACK sessionStatus
);



In julia I do the following:

Using Match

typealias Handle Ptr{Void}
typealias SessionStatus Cint

lib = string(lib_path,"/../lib/libXC")

dlopen(lib)

function getstatusdescription(v)
    @match v begin
        0 => "Disconnected"
        1 => "Connecting"
        2 => "Connected"
        3 => "Reconnecting"
        4 => "Disconnecting"
        5 => "SessionLost"
        _ => "Unknown Status Returned!"
    end
end

function onsessionstatuschanged(eSessionStatus::SessionStatus)
    status = getstatusdescription(eSessionStatus)
    println("SessionStatus: $status")
    return a::Void
end

function onloginfailed(error_str::Ptr{Uint8})
    login_error = bytestring(error_str)
 println("Error: $login_error")
    return a::Void
end


const onsessionstatuschanged_c = cfunction(onsessionstatuschanged, Void, (
SessionStatus,))
const onloginfailed_c = cfunction(onloginfailed, Void, (Ptr{Uint8},))


h_session_listener = ccall((:SessionStatusListener_create, "libXC"), Handle, 
(Ptr{Void}, Ptr{Void}),(onsessionstatuschanged_c, onloginfailed_c))


Everything seems to be fine until the ccall fails with the following error:

 ERROR: error compiling anonymous: ccall: wrong number of arguments to C 
function


Any guidance would be greatly appreciated!

Thanks!