Error sending data to Trading Network

Hi ,

Am getting the following error sometimes in my production server.

2009-01-14 11:11:15 EET [ISS.0098.0049C] Exception:com.wm.lang.flow.FlowException: Data is not properly sent to Trading Network. while executing trigger. Rejecting Document for TriggerStore:UnitMessage_Receiver.trigger:copyConditionTrigger.

These are my trigger properties for the same.

Enabled True

Join Expires After 86400000
Trigger Queue Capacity 2 (10)
Trigger Queue Refill Level 1 (4)
Acknowledgment Queue Size 1
Maximum Retry Attempts 5
Retry Interval 10000
Retry Failure Behavior Throw service exception
Resource Monitoring Service N/A
Processing Mode Serial
Max Execution Threads 1
Suspend on Error False
Exactly Once Detect Duplicates False
Exactly Once Use History N/A
Exactly Once History Time to Live N/A

NOTE: This is not happening always

Can someone please help me out how to get rid of this issue.

Thanks in advance