Maybe you should expand your spring-configuration. I'm not an expert in this issue but I think there must be beans configured in a way like this:
<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="configLocation" value="classpath:jbpm.hibernate.cfg.xml" />
<property name="dataSource" ref="dataSource" />
</bean>
<bean id="transactionManager"
class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
<property name="dataSource" ref="dataSource" />
</bean>
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
destroy-method="close">
<property name="driverClassName" value="YourDriver" />
<property name="url" value="someUrl" />
<property name="username" value="user" />
<property name="password" value="password" />
</bean>
But I don't use JBPM with Spring so I'm not confident at all.