No overload for method 'midiOutGetDevCaps' takes 2 arguments

I have a working midiInGetDevCaps console app. I was converting it to a midiOutGetDevCaps console app, and for the life of me, I'm puzzled why I get the error when it's basically identical. The error is "No overload for method'midiOutGetDevCaps' takes 2 arguments" yet, I have 2 arguments.

Perhaps another set of eyes???
Here is the complete console app code (because it's so short).

Code:

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using System;
using System.Runtime.InteropServices;
namespace MidiOutDevCaps
{
    class Program
    {
        static void Main(string[] args)
        {
            int devCount = midiOutGetNumDevs();
            Console.WriteLine(" MIDI Output devices connected: " + devCount.ToString());
            MIDIOUTCAPS outputCaps;
            for (uint oDevID = 0; oDevID < devCount; oDevID++)
            {
                midiOutGetDevCaps((UIntPtr)oDevID, out outputCaps);


                Console.WriteLine(outputCaps.szPname);
                Console.ReadKey();
            }
        }

        [DllImport("Winmm.dll", SetLastError = true)]
        public static extern int midiOutGetNumDevs();

        [DllImport("winmm.dll", SetLastError = true)]
        private static extern MMRESULT midiOutGetDevCaps(UIntPtr uDeviceID, out MIDIOUTCAPS caps,
            UInt32 cbMidiOutCaps);

        public enum MMRESULT : uint
        {
            // General return codes.
            MMSYSERR_BASE = 0,
            MMSYSERR_NOERROR = MMSYSERR_BASE + 0,
            MMSYSERR_ERROR = MMSYSERR_BASE + 1,
            MMSYSERR_BADDEVICEID = MMSYSERR_BASE + 2,
            MMSYSERR_NOTENABLED = MMSYSERR_BASE + 3,
            MMSYSERR_ALLOCATED = MMSYSERR_BASE + 4,
            MMSYSERR_INVALHANDLE = MMSYSERR_BASE + 5,
            MMSYSERR_NODRIVER = MMSYSERR_BASE + 6,
            MMSYSERR_NOMEM = MMSYSERR_BASE + 7,
            MMSYSERR_NOTSUPPORTED = MMSYSERR_BASE + 8,
            MMSYSERR_BADERRNUM = MMSYSERR_BASE + 9,
            MMSYSERR_INVALFLAG = MMSYSERR_BASE + 10,
            MMSYSERR_INVALPARAM = MMSYSERR_BASE + 11,
            MMSYSERR_HANDLEBUSY = MMSYSERR_BASE + 12,
            MMSYSERR_INVALIDALIAS = MMSYSERR_BASE + 13,
            MMSYSERR_BADDB = MMSYSERR_BASE + 14,
            MMSYSERR_KEYNOTFOUND = MMSYSERR_BASE + 15,
            MMSYSERR_READERROR = MMSYSERR_BASE + 16,
            MMSYSERR_WRITEERROR = MMSYSERR_BASE + 17,
            MMSYSERR_DELETEERROR = MMSYSERR_BASE + 18,
            MMSYSERR_VALNOTFOUND = MMSYSERR_BASE + 19,
            MMSYSERR_NODRIVERCB = MMSYSERR_BASE + 20,
            MMSYSERR_MOREDATA = MMSYSERR_BASE + 21,
            MMSYSERR_LASTERROR = MMSYSERR_BASE + 21,

            // MIDI-specific return codes.
            MIDIERR_BASE = 64,
            MIDIERR_UNPREPARED = MIDIERR_BASE + 0,
            MIDIERR_STILLPLAYING = MIDIERR_BASE + 1,
            MIDIERR_NOMAP = MIDIERR_BASE + 2,
            MIDIERR_NOTREADY = MIDIERR_BASE + 3,
            MIDIERR_NODEVICE = MIDIERR_BASE + 4,
            MIDIERR_INVALIDSETUP = MIDIERR_BASE + 5,
            MIDIERR_BADOPENMODE = MIDIERR_BASE + 6,
            MIDIERR_DONT_CONTINUE = MIDIERR_BASE + 7,
            MIDIERR_LASTERROR = MIDIERR_BASE + 7
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct MIDIOUTCAPS
        {
            public UInt16 wMid;
            public UInt16 wPid;
            public UInt32 vDriverVersion;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = (int)MAXPNAMELEN)]
            public string szPname;
            public MidiDeviceType wTechnology;
            public UInt16 wVoices;
            public UInt16 wNotes;
            public UInt16 wChannelMask;
            public MidiExtraFeatures dwSupport;
        }

        public const UInt32 MAXPNAMELEN = 32;

        public enum MidiDeviceType : ushort
        {
            MOD_MIDIPORT = 1,
            MOD_SYNTH = 2,
            MOD_SQSYNTH = 3,
            MOD_FMSYNTH = 4,
            MOD_MAPPER = 5,
            MOD_WAVETABLE = 6,
            MOD_SWSYNTH = 7
        }

        public enum MidiExtraFeatures : uint
        {
            MIDICAPS_VOLUME = 0x0001,
            MIDICAPS_LRVOLUME = 0x0002,
            MIDICAPS_CACHE = 0x0004,
            MIDICAPS_STREAM = 0x0008
        }
    }
}

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The error is with this line...

midiOutGetDevCaps((UIntPtr)oDevID, out outputCaps);

Thanks for your assistance.
Jeff

How many parameters have you defined in the PInvoke prototype?

Code:

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        [DllImport("winmm.dll", SetLastError = true)]
        private static extern MMRESULT midiOutGetDevCaps(UIntPtr uDeviceID, out MIDIOUTCAPS caps,
            UInt32 cbMidiOutCaps);

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Answer: 3, not 2