What are the properties of this file? Are you sure that it is accessible / readable by splunk?
Check its permissions. Have you tried inputing other files? Do you get any data in? what happens if you run a search for index=_internal do you see any data coming in at all?
It's an Event Viewer file. its readable by splunk, since the server has at the same directory structure some indexed files. the _internal index would be my second question. I went there to check my internal index out, but its gone. I'm running splunk on test environment, so I cleaned all the index data more than one. I guess during this test the internal index has stopped indexing.
There are numerous ways to troubleshoot this, with the following being my suggestions:
Make sure you are not indexing duplicate data/files, where the first 256 bytes might be similar. If this is happening, then you should investigate how to index duplicate files.
Run a search that specifies your exact file, all indexes, and all time. NOT using the exact file, all indexes, and all time are the most common mistake. For example, the search should resemble (select the TimeRange over All-Time):