I created a new Orchestration rule, but it is not always working & inconsistent.

Summary:

I created a new rule in "Manage Orchestration Process Assignment Rules". This is not always working and it is inconsistent. 

Content (please ensure you mask any confidential information):

As per the rule I defined, If the Order Type falls under any of the 4 order types:

(SFE RBU Order, SFE Distributor Order, SFE XSO Standing Order, SFE Buy Deal)

AND

If the order line is of a particular 'line type' called 'Minimal Order Cost, then a process called "CustomDOO_SFE_ServiceOrder_IB" must be assigned to the line. After publishing the rule, I created about 10 orders. Out of the ten, in 4 orders the line was assigned to "CustomDOO_SFE_ServiceOrder_IB" whereas for the remaining 6 orders, the line got assigned to a different Orchestration Rule. I don't see any pattern in the orders which were unsuccessful. Looks like the system randomly assigns the orchestration rule. Please let me know if I am missing something.