Hi, from your post I suppose that you are using an expression for each of the basrs. In this case note that the offset for [Late Entry Leavers] and [Joiners] should be the same. (one is supposed to substract from total and the other adds, but both bars should start at bottom of [Late Entry Leavers] because positive bars are painted from botttom to top.

[Late Entry Joiners] should add [Joiners] instead of substract them: Sum([HC Previous Month])-Sum([Leavers])-Sum([Late Entry OUT])+Sum([Joiners])