Error in workflow for distribution list.

Hello All,

Application Release: E920

Tools Release: 9.2.5.1

My custom workflow is ending in error after submitting it and in debug logs, I am getting error - (GENTEXT)ResolveSingleDistListMembers - For Dist list(30002015,RSS) did not add 1147226 to the list of members. Where 30002015 is parent AN8, RSS is Organization Type Structure and 1147226 is first level member. This same error is coming for all the members of distribution list and at the end workflow is throwing below error. 

WfActInstActionMsg::createMessages() - Distribution List <30002015,RSS> resolved in group mode to no members. 

WfActInstActionMsg::createAllMessages() : failed to create messages for WfActDefActionMsg(K550411Z,1,APPROVE)