Expression Value Missing for some rows

[#1]

1.) I have a lookup table used for assigning bucket values based on a calculated percentage. A bucket is assigned based on whether it falls in between the low and high range.

Bucket	Low Range	High Range	Start Date	End Date
A	95	99	1/1/2014	7/18/2014
B	90	94.999	1/1/2014	7/18/2014
C	80	89.999	1/1/2014	7/18/2014
D	50	79.999	1/1/2014	7/18/2014
E	0	49.999	1/1/2014	7/18/2014

2.) The 2 relevant columns on my report are Compliance % and Bucket. I am using a "Straight Table" by the way.

      My Bucket expression is defined as so (vEndDate is a variable that is set to 03/15/2014):

  = if ( $(vEndDate) >= DATE(START_DATE) AND $(vEndDate) <= DATE(END_DATE),

     if( [Compliance %] >= LOW_RANGE AND [Compliance %] <= HIGH_RANGE, BUCKET)

     )

3.) I am having a weird issue where a bucket value is displayed correctly for some rows and for other is does not for some reason.

Sample Output:

Compliance %	Bucket
98.931	A
98.940	A
98.302	-
97.256	-

Not sure where the problem is - I don't see any particular pattern in the rows that have a bucket value vs the others that do not.