datarow not updating...

[jack]

using the following code, I've been unable to write an updated xml
document.I can see the xml
file get refreshed but even at that, it writes in the original contents.
these procs come from a
databaseengine class i created, theDataStore is a dataset that gets loaded
from a xml data file
when the constructor runs.

the database engine sits in a application variable within a IIS application
and only one copy ever
exist in memory. updateUser is called via delegate.

the dataset in memory, and thus the xml file that gets written dont seem to
get updated.

public void updateUser (zDatabaseObject theObject)
{
zUser theUser = (zUser) theObject;

DataRow theRow;
theRow = theDataStore.Tables["tblUsers"].Rows.Find(theUser.UserID);

theRow["FullName"] = theUser.FullName;
theRow["UserName"] = theUser.UserName;
theRow["Password"] = theUser.Password;
theRow["Email"] = theUser.Email;
theRow.AcceptChanges();

saveDataStore();
}

private void saveDataStore()
{
theDataStore.AcceptChanges();
theDataStore.WriteXml(theRootDirectory + "zDatabase.xml");
}