Why is Datamodel=Authentication not getting older events?

[mlm]

Hey gents,

 I am very new to splunk but does anyone have an idea why my search from datamodel=authentication not getting older events (say last month or two)? Below is my search string:

| tstats prestats=true summariesonly=true allow_old_summaries=true count from datamodel=Authentication.Authentication where Authentication.app=win* Authentication.action=* by _time, Authentication.action span=10m
| timechart minspan=10m useother=true count by Authentication.action

Any suggestion would be so much appreciated! 

Cheers 

[PickleRick]

You can either disable acceleration, change the summary range and rebuild the summaries (which is not a great idea because you have to rebuild everything from scratch and summaries eat up significant amounts of space) or search without the summariesonly=true option (which will be much more intensive since you'll have to search through all the raw data fitting the dataset conditions.

Both solutions have their pros and cons.

[mlm]

@PickleRick my post got deleted lol.

Could you tell me please what the possible change would be to capture those previous months data without tampering what I have now? Basically, I just want to fill the gaps for previous months for reporting purposes