Issue in retriggering workflow when changes made for price field in PIR.

Hi Experts,

There is an issue while automatic retriggering workflow for PIR. Actually there is a logic that if the price got changed in PIR then workflow needs to retrigger automatically to the approver. Now i have 2 PIR. Let say 51XXXXXX1 and 51XXXXXX2. For both PIR the same price got changed and the workflow was retriggered for the first PIR only. Not for the second PIR. Now my question is, why the second PIR was not retriggered eventhough the same price got changed for both PIR. Can you please guide where do i need to check why the workflow was not retriggered?. Because if it's triggered and then some problem means we can check via workflow log. But since it was not retriggered obviously it will be not there in workflow log right?. Thats what i wonder where to check why the retriggered was not happend for the second PIR. Kindly give your inputs if you have expereinced towards this problem. Many thanks in advance.

Regards,

Kavi