Npgsql failed to call plpgsql function

Question

I’m running some tests on the Npgsql. One of the tests tests the return of a plpgsql function. But the test is failing saying that the function does not exist. In the error description the name in the function passed and the parameters are entered. But I am realizing that the type of the first parameter is wrong, as well as the function name as well. Below my codes.

Library Code:

using System.Collections.Generic;
using Npgsql;
using System.Data;

namespace PostgreSqlDataAccessLayer
{
    public class Dal
    {
        public string StringConnection { get; set; }
        public NpgsqlConnection Connection { get; }

        public Dal ( string stringConnection )
        {
            StringConnection = stringConnection;

            Connection = new NpgsqlConnection ( StringConnection );
        }

        public object ExecuteNoQueryOperation ( string spOrSqlInstructions, CommandType commandType = CommandType.StoredProcedure, Dictionary<string, object> parameters = null )
        {
            NpgsqlCommand npgsqlCommand = new NpgsqlCommand(spOrSqlInstructions, Connection);
            npgsqlCommand.CommandType = commandType;

            if ( parameters != null )
                foreach ( var item in parameters )
                    npgsqlCommand.Parameters.Add ( new NpgsqlParameter ( item.Key, item.Value ) );

            try
            {
                Connection.Open ( );

                return npgsqlCommand.ExecuteScalar ( );

            }
            finally
            {
                if ( Connection != null && Connection.State != ConnectionState.Closed )
                    Connection.Close ( );

                npgsqlCommand.Dispose ( );
            }
        }

        public DataSet ExecuteQueryOperation ( string spOrSqlInstructions, CommandType commandType = CommandType.StoredProcedure, Dictionary<string, object> parameters = null )
        {
            NpgsqlCommand npgsqlCommand = new NpgsqlCommand(spOrSqlInstructions, Connection);
            npgsqlCommand.CommandType = commandType;

            if ( parameters != null )
                foreach ( var item in parameters )
                    npgsqlCommand.Parameters.Add ( new NpgsqlParameter ( item.Key, item.Value ) );

            NpgsqlDataAdapter npgsqlDataAtapter = new NpgsqlDataAdapter(npgsqlCommand);
            npgsqlDataAtapter.MissingSchemaAction = MissingSchemaAction.AddWithKey;
            DataSet dataSet = new DataSet ( );

            try
            {
                npgsqlDataAtapter.Fill ( dataSet );
                return dataSet;
            }
            finally
            {
                npgsqlDataAtapter.Dispose ( );
                npgsqlCommand.Dispose ( );
            }
        }

        ~Dal()
        {
            if ( Connection != null )
                Connection.Dispose ( );
        }
    }
}

Test method:

[TestMethod]
public void TestReturnFunction ( )
{
    Dictionary<string, object> dic= new Dictionary<string, object> ();

    dic.Add ( "f_name", "Joice Silva" );
    dic.Add ( "f_age", 31 );

    pgDal = new PostgreSqlDataAccessLayer.Dal ( "Host=192.168.56.2;Username=postgres;Password=$Sat2598$;Database=Test" );

    var ret = (int)pgDal.ExecuteNoQueryOperation ( "insertPerson", parameters: dic);

    Assert.AreEqual ( 31, ret);
}

Plpgsql function:

CREATE OR REPLACE FUNCTION public."insertPerson"(
    f_name character varying,
    f_age integer)
  RETURNS integer AS
$BODY$ 
DECLARE age_ret INTEGER;
BEGIN 
    INSERT INTO "person" VALUES (f_name, f_age) RETURNING age INTO age_ret;
    RETURN age_ret; 
END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
ALTER FUNCTION public."insertPerson"(character varying, integer)
  OWNER TO postgres;

Error:

Nome de Teste:  TestReturnFunction
FullName de Teste:  DataAccessLayerTest.PostgreSqlDataAccessTest.TestReturnFunction
Fonte de Teste: C:\Users\Matheus Saraiva\OneDrive\Desenvolvimento\Sistemas\DataAccessLayer\DataAccessLayer\DataAccessLayerTest\PostgreSqlDataAccessTest.cs: linha 38
Resultado de Teste: com Falha
Duração do Teste:   0:00:00,1832631

StackTrace do Resultado:    
em Npgsql.NpgsqlConnector.DoReadMessage(DataRowLoadingMode dataRowLoadingMode, Boolean isPrependedMessage)
   em Npgsql.NpgsqlConnector.ReadMessageWithPrepended(DataRowLoadingMode dataRowLoadingMode)
   em Npgsql.NpgsqlConnector.ReadExpecting[T]()
   em Npgsql.NpgsqlDataReader.NextResultInternal()
   em Npgsql.NpgsqlDataReader.NextResult()
   em Npgsql.NpgsqlCommand.Execute(CommandBehavior behavior)
   em Npgsql.NpgsqlCommand.ExecuteScalarInternal()
   em Npgsql.NpgsqlCommand.ExecuteScalar()
   em PostgreSqlDataAccessLayer.Dal.ExecuteNoQueryOperation(String spOrSqlInstructions, CommandType commandType, Dictionary`2 parameters) na C:\Users\Matheus Saraiva\OneDrive\Desenvolvimento\Sistemas\DataAccessLayer\DataAccessLayer\PostgreSqlDataAccessLayer\Dal.cs:linha 32
   em DataAccessLayerTest.PostgreSqlDataAccessTest.TestReturnFunction() na C:\Users\Matheus Saraiva\OneDrive\Desenvolvimento\Sistemas\DataAccessLayer\DataAccessLayer\DataAccessLayerTest\PostgreSqlDataAccessTest.cs:linha 46
Mensagem de Resultado:  
Método de teste DataAccessLayerTest.PostgreSqlDataAccessTest.TestReturnFunction gerou exceção: 
Npgsql.PostgresException: 42883: function insertperson(f_name => text, f_age => integer) does not exist

By the error description, the function name is wrong (all lower case) and the type of the first parameter also (text, the correct would be varchar).