多一行無法正確輸出

問題: 底下程式碼, 如果我把 _value2 = Getfield("總流通在外股數", "Q"); 這一行當成刪掉, 才能夠正常輸出如下, 請問是為何?

if getfield("股本(億)", "D") > 0.5
then ret=1;
input: FundVol(0.5, "投信買超佔股本比(%)");
input: Length(1, "期數");
variable:_value1(0),_value2(0);
_value1 = summation(GetField("投信買張", "D"), 1);
_value2 = Getfield("總流通在外股數", "Q");
outputfield(1, _value1, 2, "投信買張");
outputfield(2, _value2, 2, "在外流通股數");