interop method call bad parameter

Question

I need to invoke the c++ library method in c# but after trying different variations still it returns an error code -2 saying that it is a bad parameter.

Here is the C++ representation of the structure that needs to be passed in as parameter:

#define ATT_MAX_USER_INFO 129
typedef struct ATTUserToUserInfo_t 
{
    ATTUUIProtocolType_t type;
    struct
    {
       short length; /* 0 indicates no UUI */
       unsigned char value[ATT_MAX_USER_INFO];
    } data;
} ATTUserToUserInfo_t;

typedef enum ATTUUIProtocolType_t 
{
    UUI_NONE = -1, /* indicates not specified */
    UUI_USER_SPECIFIC = 0, /* user-specific */
    UUI_IA5_ASCII = 4 /* null-terminated ASCII
    * character string */
} ATTUUIProtocolType_t;
/*
* ATTMakeCallConfEvent - Service Response Private Data
* (private data version 5 and later)
*/

and following is the c# representation i have created for it:

    public struct ATTUserToUserInfo_t
    {
        public ATTUUIProtocolType_t type;

        public data data;
        
    };

    public struct data
    {
        public short length;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = ATT_MAX_USER_INFO)]
        public byte[] value;
    };

and following is the interop method call which needs to be invoked:

[DllImport("ATTPRV32.dll", CharSet = CharSet.Ansi, SetLastError = true)]
public static extern Tsapi.Acs.RetCode_t attV6MakeCall(
                    [In, Out]
                    PrivateData_t privateData,
                    ref Csta.DeviceID_t_String destRoute,
                    bool priorityCalling,
                    ref Tsapi.Att.ATTUserToUserInfo_t userInfo);

Can someone please confirm if the ATTUserToUserInfo_t is correctly represented in C# so that it can be marshalled to the c++ library side as parameter ?