SPException on Feaure Activation

if (!string.IsNullOrEmpty(listName))
{
    featureParentWeb.AllowUnsafeUpdates = true;
    CreateCalendarList(featureParentWeb, listName);
    featureParentWeb.Update();
    featureParentWeb.AllowUnsafeUpdates = false;
}
else
{
    throw new SPException("The list name is not correctly set. Please check that Tech parameters list is correctly deployed and activated and that entry XXX exists.");
}