In case you are using a deployment descriptor, then the EJB name should be the same in both the descriptor file.
<ejb-jar>
<enterprise-beans>
<session>
<ejb-name>Hello</ejb-name>
<home>com.ejb.test.HelloHome</home>
<remote>com.ejb.test.HelloObject</remote>
<ejb-class>com.ejb.test.HelloBean</ejb-class>
<session-type>Stateless</session-type>
<transaction-type>Container</transaction-type>
</session>
</enterprise-beans>
<assembly-descriptor>
<container-transaction>
<method>
**<ejb-name>Hello</ejb-name>**
<method-name>*</method-name>
</method>
<trans-attribute>Required</trans-attribute>
</container-transaction>
</assembly-descriptor>
</ejb-jar>
<glassfish-ejb-jar>
<enterprise-beans>
<ejb>
**<ejb-name>Hello</ejb-name>**
<jndi-name>jndi/Hello</jndi-name>
</ejb>
</enterprise-beans>
</glassfish-ejb-jar>