[ixp1200] RmSendPacket error "Ring to microengine is full"

Hi, I use Intel's MicroACE. But there's a problem on egress side. The problem is between the core and micro block. When the core tried to send packets to micro block, there may be a RmSendPacket error, and the message is "Ring to microengine is full". Who can give me some help? Regards. Irvin