My Customer have IDM 4.5

They have a text file as an authoritative source of user accounts.

They need to turn off the Delimited Text Driver if the file has more than 40 records of users.

They have configured the driver health follows ,

<driver-state state="running"/>
<transactions op="gt" over-last="1" source="publisher-reported-events" transaction="add" value="40"/>

but the process does not work .

How should they configure the rule so that the driver turns off if the file has more than 40 records?