missing icon next to numerical column on Fields pane

snapshot from the Fields paneNormally there is a tiny summation icon next to those column names having whole number as the data type. However, if I take a look at the Fields pane image as attached, it seems not the case.  There is no such icon next to “Amount” of Actuals table and “Amt” of Budget table respectively while the corresponding “Amount” and “Amt” columns of FunctionfnBlend table do have that icons. Is some one would like to explain for me what’s the difference and how to adapt the same logic to the mentioned columns of Actuals table & Budget table?