Don't know. That is quite old‑fashioned code;
you should use the new Date classes rather than java.util.Date.
One thing: you should close the “outside” objects. Your outermost reader is the line number reader, so you close that, and you don't need to close the other two readers. Your outermost writer is the buffered writer but you haven't closed that. If you don't close the buffered writer you may never flush it and you get nothing in the output file. Not sure whether that is the cause of your problem, but it is worth considering.
Suggest:
Close only the lnr and the bw. Find out how to open the writers with
try‑with‑resources and you can forget about closing because it is all done automatically.