[amibroker] still struggling with Sum() and Cum()

[bigitop]

ok, here's my big problem.  consider this example:

m = IIf(Open > 48 & Open < 52, 1, 0);

number = Cum(m);
result = LastValue(number);

Filter = m == 1;

AddColumn(Open, "Open");
AddColumn(result,"result");

running this code in the Analysis window returns:

total rows:    356 rows
highest number in "result":   450

so, first of all, shouldn't they be the exact same number and
secondly, shouldn't "result" be filled with just one value as opposed to
many values?

neither of this is happening.  what am i doing wrong?!