here my interface for the previous error
package suncertify.db;
import java.io.*;
import java.util.*;
import java.rmi.*;
import java.rmi.Remote;
import suncertify.db.DataInfo;
import suncertify.db.FieldInfo;
public interface DataClient extends Remote
{
public FieldInfo [] getFieldInfo()throws RemoteException;
public DataInfo getRecord(int recNum)throws DatabaseException,RemoteException;
public DataInfo find(String toMatch)throws DatabaseException, RemoteException;
public void add(String [] newData)throws DatabaseException,RemoteException;
public void modify(DataInfo newData)throws DatabaseException, RemoteException;
public void delete(DataInfo toDelete)throws DatabaseException, RemoteException;
public void close() throws RemoteException;
public void lock(int record)throws IOException, RemoteException;
public void unlock(int record)throws RemoteException;
public DataInfo[] criteriaFind(String criteria)throws DatabaseException, RemoteException;
public String[] getComboValues(int fieldNum) throws DatabaseException, RemoteException;
public int getRecordCount() throws RemoteException;
}