Inconsistent IF Results

CELL A1 CONTAINS "4.030"
CELL B1 CONTAINS "4.015"
CELL C1 HAS THIS FORMULA =SUM(A1-B1).....IN THIS CASE THE SUM IS ".015"
CELL D1 HAS THIS FORMULA =IF(C1>0.015,"FAIL","PASS"), BUT......
IT RETURNS "FAIL", ANYTHING OVER OR UNDER THE EXACT NUMBER WORKS FINE, BUT THE EXACT NUMBER ISN'T ACTING RIGHT!
ALSO, IF I REMOVE THE FORMULA FROM C1 & MANUALLY TYPE ".015" INTO THE CELL IT WORKS GREAT AS WELL.
HELP ME!!!!!!
please