error "does not implement interface member" In WCF C#

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C#

WCF

Hi I Have Error in my WCF app
i want to using a class in WCF application

.CS File

namespace AccessService
{
  [ServiceContract]
    public interface IService1
    {

        [OperationContract]
        string GetData(int value);

        [OperationContract]
        string GetProvider(string IP, string Serial);

        [OperationContract]
        DatabaseProviderProp SendConnectionProv(DatabaseProviderProp Composite);

    }


 [DataContract]
    public class DatabaseProviderProp
    {

        string ServIP;
        string DbName;

        [DataMember]
        public string ServerIP
        {
            get { return ServIP; }
            set { ServIP = value; }
        }

        [DataMember]
        public string DatabaseName
        {
            get { return DbName; }
            set { DbName = value; }
        }

    }
}

.SVC.CS File

namespace AccessService
{
    public class AccessServ : IService1
    {
        public string GetData(int value)
        {
            return string.Format("You entered: {0}", value);
        }

        public string GetProvider(string IP, string Serial)
        {
            ConnectionProviders ConProv = new ConnectionProviders();

            if (ConProv.CheckIP(IP) == true)
            {
                if (ConProv.SearchSerial(Serial) == true)
                {
                    return "Ok";
                }
                else
                {
                    if (ConProv.ExProperty == null)
                    {
                        return "Eror In Serial Or Your Requst IP";
                    }
                    else
                    {
                        return ConProv.ExProperty;
                    }
                }
            }
            else
            {
                if (ConProv.ExProperty == null)
                {
                    return "Eror In Serial Or Your Requst IP";
                }
                else
                {
                    return ConProv.ExProperty;
                }
            }
        }

        

        public  DatabaseProviderProp SendConnectionProv(string Serial)
        {
 			 DatabaseProviderProp Database = new DatabaseProviderProp();
            Database.DatabaseName = "Hi All";
            return Database;
        }
    }
}

Error In "AccessServ" Class
I do not want to add DatabaseProviderProp class in SendConnectionProv as parameter but when i do that error hide
i want to add a "Serial" as a parameter and the DatabaseProviderProp as variable

thanks...