checkbox doesn't check in dataTable

So I have a small bug to fix, this part of code isn't written by me, so I don't really know why this happening.

So there is a <p:dataTable> in a <p:tab>

and first collumn is just a a checkBox to put a checkMark on particular row or to check all rows in a table.

So when I check first checkbox it checks every row, but it doesn't put a check mark on it's self..

Any ideas why is that?

thats the code for this collumn:

using JSF , primefaces 5.1