Java EE (Java Enterprise Edition) General Discussion

I have got a very simple Session bean. Now I am trying to call a class from this bean with the following error:

class invalid for deserialization

Not sure about the detail about the error but I tried doing lots of things with no success .. Please help!

I have a class (see below) is being called by EJB as showns ..
....

Row[] arrSort = new Row[marrRows.size()];
arrSort = (Row[]) marrRows.toArray(arrSort);
Arrays.sort(arrSort, new RowComparator());
ArrayList al = new ArrayList(Arrays.asList(arrSort));

....


----------------------- class source ------------------------
package org.uabhs.svcs.pagination.impl;

import java.io.IOException;
import java.io.Serializable;

public class Row implements Serializable {

public Object[] columns;
public int[] columnSortOrder;
public Row(int[] sortOrder) {
columnSortOrder = sortOrder;
}

public String toString() {
String sReturn = "";

for (int i = 0; i < columns.length; i++) {
try {
sReturn += (columns.toString() + "|");
} catch (Exception e) {
sReturn += "|";
}
}

return sReturn;
}
}