Error: The structure must not be a value class. parameter name structure

Question

 public struct Alert_Cue_Type
            public short Test_Mode;
            public short WXR_Aural_Alert_Requests;
public struct AURAL_TYPE
            public Alert_Cue_Type Alert_Cue;
            public ushort Checkword;
            public ushort PacketId;
            public short pad;
            public ushort Payload_Size;
            public ushort WordId;
char[] Buffer = new char[3200];
Buffer=ReceiveData();
AURAL_TYPE Alerts = new AURAL_TYPE();
int AURAL_TYPE_Size = Marshal.SizeOf(Alerts);
IntPtr ptr = Marshal.AllocHGlobal(AURAL_TYPE_Size);
Marshal.Copy(Buffer, 6, ptr, AURAL_TYPE_Size);
Marshal.PtrToStructure(ptr, Alerts);//Error as mentioned in title
 How to fix it?

Answer 1

take a look at this solution please:
http://stackoverflow.com/questions/1195685/argument-exception-error-type-question
I think you need this modification based on the solution suggestion in the link:
(AURAL_TYPE)Marshal.PtrToStructure(ptr, typeof(AURAL_TYPE));