hashmap serialize

I am using jdk 1.6 and thought serializing hashmap would be a cinch

I got
    HashMap<String, RegexRecord> myRegexHolder;
    String sRegexHolderFile = "c:\data\.regexHolderObj.ser";

    if ( (new java.io.File(strRegexHolderObjFSpec)).exists()) {
            // restore myRegexHolder previously serialized
            boolean bFailed = false;
            try {
                // read and deserialize the blob
                FileInputStream fileIn = new
FileInputStream(strRegexHolderObjFSpec);
                ObjectInputStream ois = new ObjectInputStream(fileIn);
                myRegexHolder = (HashMap<String, regextest.RegexRecord>)
ois.readObject();
// oops Got warning: D:\proj\Util\RegexTest\src\regextest\RegexTest.java:55:
warning: [unchecked] unchecked cast

                //myRegexHolder = myRegexHolder.readObject(ois);
                ois.close();
            } catch (ClassNotFoundException ex) {
                setStatus("Exception in deSerializing myRegexHolder: " +
ex.getMessage());
                ex.printStackTrace();
                bFailed = true;
            } catch (IOException ex) {
                setStatus("Exception in deSerializing myRegexHolder - IO
error: " + ex.getMessage());
                ex.printStackTrace();
                bFailed = true;
            }

            if ( bFailed == false) setStatus("restore myRegexHolder
successfully from user file");

        } else {
            // create empty myRegexHolder
            myRegexHolder = new HashMap<String, RegexRecord>(180,
(float)0.75);
            setStatus("Created myRegexHolder successfully for initial
capacity of 180 and 75% load factor");
        };
    }

...... some processing that results adding, updating the hsahmap of
myRegexHolder
.... before closing or at user request save the hashmap\ to external file

 private void saveRegexHolder() {

    //serialize myRegexHolder
        myRegexHolder.writeToObject();
// oops , error: D:\proj\Util\RegexTest\src\regextest\RegexTest.java:499:
cannot find symbol
 )

......
}

please help, thank you for your time and effort