Using Aggr() in Histogram Dimension

[TNAM]

Hello, 

I'm having trouble with creating a calculated dimension for a histogram in Qliksense. 

As shown in the image below,  I was hoping to create a set of ranges on the x-axis : 0%, 1~5%, 6~10%, 11~15%, etc. However, for some reason, the chart will not generate 1~5%  range and instead, those data points are grouped with 0%.  For instance, the value of 0.05 will be grouped into 0% (as shown in the image below in Aggr Expr - Dimension column). Funny thing is that when I put the same expression as a measure (Aggr Expr - Measure), it seems to be working fine.  
What could be happening here? 

This is the expression I used to calculate those ranges:

=aggr(
   if(
          only({$} TEST_PERCENTAGE) = 0, dual('0%', 0)
          , dual(
                 num((div(only({$} TEST_PERCENTAGE) - 0.01, 0.05) * 5) + 1, '###0') & '-' & num((div(only({$}                                           TEST_PERCENTAGE) -  0.01, 0.05) + 1) * 0.05, '###0%')
             ,  div(only({$} TEST_PERCENTAGE) - 0.01, 0.05
          )
       )
    ), TEST_PERCENTAGE
)

TEST_PERCENTAGE values contain test percentages in decimals (e.g. from 0.05 to 0.80)