Jboss- DataSource Problem

I have Jboss 4.0.1 and mysql4.1 and j2sdk1.4.2_07. i have deployed a ear file which contains 1 entity bean . I get the following errors when i start the server

ObjectName: jboss.j2ee:jndiName=ejb/Example/Story,service=EJB
state: FAILED
I Depend On:
Depends On Me: org.jboss.deployment.DeploymentException: Error: can't find data
source: java:/MySqlDS; - nested throwable: (javax.naming.NameNotFoundException:
MySqlDS not bound)

and in the browser i get following error

java.rmi.ServerException: RuntimeException; nested exception is: java.lang.IllegalStateException: createBeanClassInstanceCommand == null

Can somebody please help me with this problem .

Hi,
My problem is solved. I followed the steps mentioned below

1.Replace jboss-4.0.0/server/standard/deploy/hsqldb-ds.xml by a file named mysql-ds.xml with the following content:
<datasources>
<local-tx-datasource>
<jndi-name>DefaultDS</jndi-name>
<connection-url>jdbc:mysql://localhost/test</connection-url>
<driver-class>com.mysql.jdbc.Driver</driver-class>
<user-name>jboss</user-name>
<security-domain>MySqlDbRealm</security-domain>
</local-tx-datasource>
</datasources>
2.Edit jboss-4.0.0/server/standard/conf/standardjaws.xml with the following parameters:
<datasource>java:/DefaultDS</datasource>
<type-mapping>mySQL</type-mapping>

3.Edit jboss-4.0.0/server/standard/conf/standardjbosscmp-jdbc.xml with the following parameters:
<datasource-mapping>mySQL</datasource-mapping>
...
<fk-constraint>true</fk-constraint>

4.Replace file jboss-4.0.0/server/standard/deploy/jms/hsql-jdbc2-service.xml by file jboss-4.0.0/docs/examples/jms/mysql-jdbc2-service.xml and change MySqlDs to DefaultDS (line 47) in that file.