Error installing Gallery Core (I'm installing gallery2 with DB2 via ibm_db2 extension)

Gallery version (not just "2"): 2.3
PHP version (e.g. 5.1.6): 5.2.3
PHPInfo Link (see FAQ):
Webserver (e.g. Apache 1.3.33):
Database (e.g. MySql 5.0.32): DB2 v9.5.0.808 (installed locally)
Activated toolkits (e.g. NetPbm, GD):
Operating system (e.g. Linux): Windows XP SP2
Browser (e.g. Firefox 2.0): Firefox 3.5

twitter.com/shawnzhu

I'm installing Gallery2 with DB2. The installation fails in step 8: "Install Gallery Core" with messages like this:
Unable to install the core module Unable to activate the core module
Error installing Gallery Core

Could anyone here can help me to find what this error means? Thanks.
The stack trace:
Error (ERROR_STORAGE_FAILURE) : Create Sequence failed for sequence: SequenceLock

* in modules\core\classes\GalleryStorage\GalleryStorageExtras.class at line 2179 (GalleryCoreApi::error)
* in modules\core\classes\GalleryStorage\GalleryStorageExtras.class at line 1273 (GalleryStorageExtras::createSequence)
* in modules\core\classes\GalleryStorage.class at line 768 (GalleryStorageExtras::configureStore)
* in modules\core\classes\GalleryStorage\Db2Storage.class at line 139 (GalleryStorage::configureStore)
* in modules\core\classes\GalleryModule.class at line 156 (Db2Storage::configureStore)
* in install\steps\InstallCoreModuleStep.class at line 138 (GalleryModule::installOrUpgrade)
* in install\index.php at line 164 (InstallCoreModuleStep::processRequest)

Error (ERROR_STORAGE_FAILURE)

* in modules\core\classes\GalleryStorage.class at line 494 (GalleryCoreApi::error)
* in modules\core\classes\GalleryStorage.class at line 1290 (GalleryStorage::search)
* in modules\core\classes\GalleryStorage.class at line 1237 (GalleryStorage::_getEntityOrMapInfo)
* in modules\core\classes\GalleryStorage\GalleryStorageExtras.class at line 1067 (GalleryStorage::describeMap)
* in modules\core\classes\GalleryStorage.class at line 533 (GalleryStorageExtras::removeMapEntry)
* in modules\core\classes\GalleryCoreApi.class at line 2935 (GalleryStorage::removeMapEntry)
* in modules\core\classes\helpers\GalleryFactoryHelper_medium.class at line 96 (GalleryCoreApi::removeMapEntry)
* in modules\core\classes\GalleryCoreApi.class at line 241 (GalleryFactoryHelper_medium::unregisterImplementationsByModuleId)
* in modules\core\CoreModuleExtras.inc at line 3383 (GalleryCoreApi::unregisterFactoryImplementationsByModuleId)
* in modules\core\module.inc at line 556 (CoreModuleExtras::performFactoryRegistrations)
* in modules\core\classes\GalleryModule.class at line 410 (CoreModule::performFactoryRegistrations)
* in install\steps\InstallCoreModuleStep.class at line 153 (GalleryModule::activate)
* in install\index.php at line 164 (InstallCoreModuleStep::processRequest)