Blog API crash

I am trying to use Windows Live Writer 14 via Blog API. However, when I try to publish, Live Writer is giving the error "The response to the metaWeblog.newPost method received from the blog server was invalid: Invalid response document returned from XmlRpc server".

I checked the error log and saw that Drupal is sending the error message "__clone method called on non-object in C:\Project\drupal\includes\common.inc on line 1685".

I get the same error when I switch to "WLW Blog API" module, too.

Watchdog's log in the database is as follows:

1023 1 user Session opened for %name. a:1:{s:5:"%name";s:5:"Al";} 5 http://localhost/drupal/xmlrpc.php 127.0.0.1 1234058798

I used Trace to find the error source. Its log is as follows:

#bff86438 T=0.000000 [REQUEST] 2009-02-08 10:57:19.551128 POST /drupal/xmlrpc.php HTTP/1.1
#bff86438 T+0.005568 [HOOK ] hook_boot:
#bff86438 T+0.007922 [HOOK ] hook_xmlrpc: blogapi
#bff86438 T+0.011440 [HOOK ] hook_user: block, blog, comment, contact, dblog, locale, node, openid, poll, profile, statistics, system, trigger, user, userreference, date_timezone, googleanalytics, imagecache, imagecache_profiles, wysiwyg, pathauto, i18n, drupalforfirebug
#bff86438 T+0.027987 [HOOK ] hook_watchdog: dblog, syslog
#bff86438 T+0.029633 [HOOK ] hook_user: block, blog, comment, contact, dblog, locale, node, openid, poll, profile, statistics, system, trigger, user, userreference, date_timezone, googleanalytics, imagecache, imagecache_profiles, wysiwyg, pathauto, i18n, drupalforfirebug
#bff86438 T+0.038655 [HOOK ] hook_node_info: blog, poll, image, forum
#bff86438 T+0.040422 [HOOK ] hook_db_rewrite_sql: node, i18nblocks, i18n, i18ntaxonomy
#bff86438 T+0.044377 [NOTICE ] E_NOTICE: Undefined index: mt_excerpt in `modules\blogapi\blogapi.module':871
if ($struct['mt_excerpt']) {
#bff86438 T+0.046344 [NOTICE ] E_NOTICE: Undefined index: mt_convert_breaks in `modules\blogapi\blogapi.module':879
if ($struct['mt_convert_breaks']) {
#bff86438 T+0.048590 [NOTICE ] E_NOTICE: Undefined index: dateCreated in `modules\blogapi\blogapi.module':884
if ($struct['dateCreated']) {
#bff86438 T+0.050755 [RESPNSE] 2009-02-08 10:57:19.600528 200 OK