Priced item 75, recieved only 71, Where did the 4 Go?

[Alexacroft]

So i had a very round number on my $L count 20100 and i looked in the history again just a few moments ago and i had a sale of an item that was 75$L my balance is 20171$L. there are no other Revenue Distributions other then me

[Alwin Alcott]

MP sale?... it's gone to LL as fees