Confusion in getHeaderByName methods - Please help

[PILLAI,RANJITH (HP-PaloAlto,ex1)]

Hi,

Could somebody explain me the difference between below given API's.
Unfortunately I couldn't figure out from API documentation.

1) public SOAPHeaderElement getHeaderByName(java.lang.String namespace,
                                         java.lang.String localPart)
                                  throws AxisFault
        Get a header by name (always respecting the currently in-scope
actors list) 

AxisFault

2) public SOAPHeaderElement getHeaderByName(java.lang.String namespace,
                                         java.lang.String localPart,
                                         boolean accessAllHeaders)
                                  throws AxisFault 

        Get a header by name, filtering for headers targeted at this engine
depending on the accessAllHeaders parameter.

In my service I used the first API. This worked fine, but when I ported my
service to a different system, it failed.  I am wondering why... I don't
have any actors defined.

Any feed back will be really appreciated..

Thanks,
Ranjith Pillai.