Reasons for %Lookup failure

I am having a problem with the %Lookup BIF.  I am performing a %Lookup on an
array that has the value in it (I have debugged), and yet the %Lookup does
not produce the index number of the array element.  

The array is very simple:
D SiteCursor      S              3A   Inz(*Blanks)
D                                     Dim(300)    
D                                     Ascend 

I read through a file (in Key order, the key being the value that will fill
in the SiteCursor elements), and populate each element in the array with the
site ID value (3 Alpha).  I am also populating a similar element of a data
structure array, which will hold numerics.  

Once populated, I read through an accounts file, and for each record, I
%lookup the site ID in the SiteCursor array:

ElemNumber=%Lookup(Fmacro:SiteCursor);


I then use the ElemNumber index value to add up dollar amounts from the
accounts file, in the other data structure array:

Sitesum(ElemNumber).SumChgs += Fmcrch;


In debugging, for some reason, the %Lookup never works.  I have verified
that the array contains the element being looked up, but it fails to place
any value in the ElemNumber variable.  I know the values are in order in the
SiteCursor array, so I don't do a SortA, because this would sort all of the
blanks to the top.  Does a SortA need to be run for %Lookup to work?



Tony Carolla
MedAmerica Billing Services, Inc.