"No identifier/primary key specified for Entity" problem, Doctrine Beta 3 cannot find primary key

when execute

php doctrine.php orm:convert-mapping --from-database annotation "Entities"

get error message

No identifier/primary key specified for Entity 'Classname(Tablename)'. Every Entity must have an identifier/primary key.

For resolving this problem
I've replaced the line

public function loadMetadataForClass($className, ClassMetadataInfo $metadata)
{
...
$indexes = $this->tables[$tableName]->getIndexes();
...
}

in function "loadMetadataForClass" in \\Doctrine\ORM\Mapping\Driver\DatabaseDriver.php by

public function loadMetadataForClass($className, ClassMetadataInfo $metadata)
{
...
$indexes = $this->_sm->listTableIndexes($tableName);
...
}

then the beta 3 works for my date base

It is because doctrine look for $indexes['prime'] to construit the primary key in entities. when we use "$this->tables[$tableName]>getIndexes()", the keys in $indexes are the real name of indexes of the data base, and in my database, the primary key indexes are named PK_TABLENAME. So I have to use $this>_sm->listTableIndexes($tableName) to pre-edit the indexes before get the list