Add the following in your search before displaying the table.
| search eventcount>=1 AND InvocationType!="ACK" |
Transaction command adds eventcount and duration fields to a search. Eventcount gives a list of events that are grouped together based on the transaction id i.e. CorrelationID in your case. Similarly duration is the difference of first and last event matched by transaction in seconds. If you are getting it as 0, it implies you have only single event in the transaction.
In order to test transaction you can add CorrelationID=<Your Sample Correlation ID with multiple events> to your base search.
Transaction is an expensive command if run for long duration of time and might drop data. You should consider using startswith, endswith, keepevicted, keeporphaned, maxpause and maxspan parameters based on your use case. Infact, you should also explore stats instead of transaction which will return results faster.
Refer to the following documentation on Splunk event correlation commands to be used based on various use cases: http://docs.splunk.com/Documentation/Splunk/latest/Search/Abouteventcorrelation
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