Undefined reference to...function returning pointer

Making a header to connect to PostgreSQL database I'm encapsulating libpq functions into functions of my own but, in one of them, which supposedly returns a pointer of type PGconn I get an error of the type...

ConexionPostgres.c:32:6: aviso: la asignación crea un puntero desde un entero sin una conversión [activado por defecto] /tmp/ccCeaewL.o: In functionmain': ConexionPostgres.c:(.text+0x86): undefined reference tosetBD'

I thought it was because of the prototype so I changed the proto and put the definition directly before main but nothing...Could someone tell what's going on?

I'm checking Postgres libpq documentation and libpq-fe.h directly to see the proto's so I'm not missing anything but I've confused. Here's my code:

PGconn *setDB(char *conninfo)
{
    PGconn *db;
    db = PQconnectdb(conninfo);

    if(!db)
          printf("Error en conexion a la BD");

    if(PQstatus(db) != CONNECTION_OK)
    {
      printf( "%s\n", PQerrorMessage(db));
    }
    else
    {
        return db;
    }

}

int main()
{

      const char *conninfo = "dbname='database' host='somehost' user='me' password='somepass'";
    //char *query = "INSERT INTO productos VALUES ('1','5','235')";

    PGconn *con;
    con = setBD(conninfo); /* --> Here's apparently the problem */  

    PQfinish(con);
    exit(0);

}