eviction fails in jdbc cache-store

<local-cache name="sample">
    <transaction mode="NON_XA" locking="PESSIMISTIC"/>
    <eviction strategy="LRU" max-entries="100"/>
    <string-keyed-jdbc-store datasource="java:jboss/datasources/PostgresqlDS" shared="false" preload="false" passivation="false" purge="false">
        <write-behind flush-lock-timeout="1" modification-queue-size="1024" shutdown-timeout="25000" thread-pool-size="1"/>
        <property name="databaseType">
            POSTGRES
        </property>
        <string-keyed-table prefix="wcm_content">
            <id-column name="id" type="VARCHAR(200)"/>
            <data-column name="datum" type="BYTEA"/>
            <timestamp-column name="version" type="BIGINT"/>
        </string-keyed-table>
    </string-keyed-jdbc-store>
</local-cache>