Data Lables, in chart go away when reopening

I've got a pivot table with the sales reps name in the row, month sold in the
column and for different sales figure "sums" in the data.

I've created a standard column chart to compare these 4 different "sums"
(which become my category axis), by rep for a given month and even though I
format the data series to have data labels (value or $), everytime I close
and reopen my workbook the data lables are gone.

Is there anyway to make these lables stay so when I reopen my workbook they
are still there?