how to export a struct array in a struct?

I want to export a structure from C# to an unmanaged delphi application, that I can not change.

The structure in unmanaged looks like this:

TDCRecEx = record
    Name: PChar; // name of item
    value: PChar; // value of item
        Socket: Integer; // socket to send to
        quality: Integer; // quality of value
end;
PDCRecEx = ^TDCRecEx;

TDCRecList = record
    Len : Integer;                     // count of pointer
    Ptr : Array of PDCRecEx;      // pointer array to record
end;
PDCRecList = ^TDCRecList;

The unmanaged code calls the exported C# function with a pointer to the TDCRecList struct -> PDCRecList: definition:

dRecList: PDCRecList;
procedure getRecList(dRL:PDCRecList); stdcall; external 'ClassLibrary1.dll';

call: getArrayStruct(dRecList); //pointer will be 'nil' -> a nullpointer

I did not manage to export the structure in C#. In delphi dRecList will be null. I am using an array with size of only 1 at this point. What I have is this:

private struct Rec
{
    public IntPtr name;
    public IntPtr value;
    public int socket;
    public int qual;
}

private struct RecList
{
    public int len;
    public IntPtr records;  //will point to an array of Intptr
}

My export function looks like this:

[DllExport]
public static void getRecList(IntPtr pdRL)
{
    Rec rec;
    rec.name = new UnmanagedString("Tag1", UnmanagedString.SType.Ansi);
    rec.value = new UnmanagedString("value 100", UnmanagedString.SType.Ansi);
    rec.socket = 123456;
    rec.qual = 192;

    RecList recList;
    recList.len = 1;

    //create a pointer array, to point to from recList.records
    //and add an unmanaged structure to it
    IntPtr[] recArr = new IntPtr[1];
    recArr[0] = new UnmanagedStructure(rec);

    //allocation for recList.records
    int size = Marshal.SizeOf(rec);
    recList.records = Marshal.AllocHGlobal(size);

    //point to the pointer array from recList.records
    Marshal.Copy(recArr, 0, recList.records, 1);

    //make an unmanaged structure for recList
    pdRL = new UnmanagedStructure(recList);
}

As said, in delphi there will be a nullpointer and I don't know why.

Can you please help me? How would you do it?

3F / DllExport

how to export a struct array in a struct? #116