Enterprise SAP Adapter: No pc group active to end

Problem about operation configuration for SAP ALE/IDoc Server Adapter.

SunOS 5.8
Enterprise Server 4.1.1 SP16
Adapter : SAP ALE/IDoc Server Adapter 4.1.1 SP6
Operation: ALEProcessOutbound Operation
Tab : IDoc

After applying SP6 to SAP adapter,
it throws “No pc group active to end” to reload IDoc structure information by clicking “reload button”.
This error occurs to a specified adapter, not to every adapter.
The same adapter’s reload operation works fine with SP3.

“No pc group active to end”
Does anyone know what this means and why this occurs?