NullPointerException while running testcases

Hello Torque-Users,

while executing the junit testcases for my webapp I get the following 
exception trying to
save a new record to the database (I'm using torque 3.1 with an oracle 
database):

| +------------------
| | Nested Exception: java.lang.NullPointerException
| | Message: null
| | Stack trace:
java.lang.NullPointerException
        at org.apache.torque.util.BasePeer.doInsert(BasePeer.java:697)
        at 
dtag.dns.torque.BaseOrdersPeer.doInsert(BaseOrdersPeer.java:258)
        at 
dtag.dns.torque.BaseOrdersPeer.doInsert(BaseOrdersPeer.java:634)
        at dtag.dns.torque.BaseOrders.save(BaseOrders.java:976)
        at dtag.dns.torque.BaseDnsObject.save(BaseDnsObject.java:107)
        at dtag.dns.torque.Orders.save(Orders.java:56)
        at dtag.dns.orders.Order.execute(Order.java:194)
        at dtag.dns.orders.Order.execute(Order.java:90)

Looking thru the torque code and doing some logging, I found out, that the 
table to which I
want to save is not contained in the table map (BasePeer.java, line 696). 
The funny thing is
that this occurs only when I run the testcases (I'm using strutstestcases 
2.1.3 with struts 1.2.4).
Normaly the app is runnung with apache and tomcat, If so, there's no 
exception and the table
is contained in the table map.

Does anyone has faced this or a similar problem and has got a solution or 
hint for me ?

Thanks in advance,
Arndt