Line D SC 1040 Ad Back

When attempting to enter "add back" federal exempt dividends to SC 1040 from two different brokerages, only one brokerage amount of fed exempt dividends appears on line D of SC 1040.  The second brokerage amount of fed exempt does not get added.  Can delete the first brokerage fed exempt amount from federal 1040 and enter the second brokerage fed exempt amount and that amount will appear on line D.  Can not get the total amount from both brokerages to get entered on line D.