How to get output from a winapi based DeviceIOControl function?

just started with my first steps using the WinAPI calling functions.

So here is the Code:

public enum EMethod : uint
    {
        Buffered = 0,
        InDirect = 1,
        OutDirect = 2,
        Neither = 3
    }

    [Flags]
    public enum EFileDevice : uint
    {
        CDRom = 0x00000002,
        Disk = 0x00000007,
        VirtualDisk = 0x00000024
    }
    [Flags]
    public enum EIOControlCode : uint
    {
        DiskGetDriveGeometry = (EFileDevice.Disk << 16) | (0x0000 << 2) | EMethod.Buffered | (0 << 14),
        DiskGetDriveGeometryEx = (EFileDevice.Disk << 16) | (0x0028 << 2) | EMethod.Buffered | (0 << 14),
        DiskGetPartitionInfo = (EFileDevice.Disk << 16) | (0x0001 << 2) | EMethod.Buffered | (FileAccess.Read << 14),
        DiskGetPartitionInfoEx = (EFileDevice.Disk << 16) | (0x0012 << 2) | EMethod.Buffered | (0 << 14),
        DiskSetPartitionInfo = (EFileDevice.Disk << 16) | (0x0002 << 2) | EMethod.Buffered | (FileAccess.ReadWrite << 14),
        DiskPerformance = (EFileDevice.Disk << 16) | (0x0008 << 2) | EMethod.Buffered | (0 << 14),
        DiskIsWritable = (EFileDevice.Disk << 16) | (0x0009 << 2) | EMethod.Buffered | (0 << 14),
        DiskControllerNumber = (EFileDevice.Disk << 16) | (0x0011 << 2) | EMethod.Buffered | (0 << 14),
        DiskUpdateDriveSize = (EFileDevice.Disk << 16) | (0x0032 << 2) | EMethod.Buffered | (FileAccess.ReadWrite << 14),
        DiskGrowPartition = (EFileDevice.Disk << 16) | (0x0034 << 2) | EMethod.Buffered | (FileAccess.ReadWrite << 14),
        DiskFindNewDevices = (EFileDevice.Disk << 16) | (0x0206 << 2) | EMethod.Buffered | (FileAccess.Read << 14),
        DiskCreateDisk = (EFileDevice.Disk << 16) | (0x0016 << 2) | EMethod.Buffered | (FileAccess.ReadWrite << 14),
        DiskGetLengthInfo = (EFileDevice.Disk << 16) | (0x0017 << 2) | EMethod.Buffered | (FileAccess.Read << 14)
    }
    [DllImport("Kernel32.dll", SetLastError = false, CharSet = CharSet.Auto)]
    public static extern bool DeviceIoControl(
    SafeFileHandle hDevice,
    EIOControlCode IoControlCode,
    [MarshalAs(UnmanagedType.AsAny)]
    [In] object InBuffer,
    uint nInBufferSize,
    [MarshalAs(UnmanagedType.AsAny)]
    [Out] object OutBuffer,
    uint nOutBufferSize,
    ref uint pBytesReturned,
    [In] IntPtr Overlapped
    );
    [DllImport("Kernel32.dll", SetLastError = true)]
    static extern Microsoft.Win32.SafeHandles.SafeFileHandle CreateFile(string filename, [MarshalAs(UnmanagedType.U4)]FileAccess fileaccess, [MarshalAs(UnmanagedType.U4)]FileShare fileshare, int securityattributes, [MarshalAs(UnmanagedType.U4)]FileMode creationdisposition, int flags, IntPtr template);

Calling the functions here:

                int size = 600;
                uint usize = 600;
                uint bRet = 0;


                IntPtr p = Marshal.AllocHGlobal(size);

                var safeFileHandle = CreateFile("\\\\.\\C", FileAccess.ReadWrite, FileShare.ReadWrite, 0, FileMode.Create, 0, IntPtr.Zero);
                DeviceIoControl(safeFileHandle, EIOControlCode.DiskGetPartitionInfo, IntPtr.Zero, 0, p, usize,ref bRet,  IntPtr.Zero);

Why is bRet returning 0 ?

Shouldn't be bRet filled with the data from the Execution ?

What am i doing wrong ?

If i log this to the Console, bRet still showing 0.

The SafeFileHandler is pointing to the C Drive (i hope this is correct).

My Main Goal is to achive data from the function, that i can use for future operations.