WebLogic Exception in onMessage: String index out of range: -1

We got the following exceptions in our WebLogic log, what could be the cause?

####<Nov 22, 2011 2:40:23 AM EST> <Warning> <EJB> <jamu66> <PRO1server>
<[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default
(self-tuning)'> <<anonymous>> <
> <> <1321947623385> <BEA-010065> <MessageDrivenBean threw an Exception in
onMessage(). The exception was:
java.lang.StringIndexOutOfBoundsException: String index out of range: -1.
java.lang.StringIndexOutOfBoundsException: String index out of range: -1
       at java.lang.String.substring(String.java:1937)
       at
com.mslv.asap.activation.srp.ErrorResponseBean.getExceptionName(ErrorResponseB
ean.java:100)
       at
com.mslv.asap.activation.srp.ErrorResponseBean.onMessage(ErrorResponseBean.jav
a:83)
       at
weblogic.ejb.container.internal.MDListener.execute(MDListener.java:466)