%Lookup on non-qualified DS array subfield

Is it possible? I need to do both a %Lookup on a DS array subfield as well
as a SortA. The %lookup works fine on a stand-alone field, but when I put
the array inside a DS for the purpose of sorting corresponding elements in
other arrays, it doesn't. Based on code form a co-workers program, it
appears that the regular LOOKUP op-code will work, but I am using
free-format and would like to avoid using fixed-width code for just that
operation. Here is the relevant code:

START CODE ----

d ds
d dsTots 26a dim(ARRAY_SIZE)
d depDats 8s 0 overlay(dsTots) inz
d apmTots 9s 2 overlay(dsTots: *next) inz
d cllTots 9s 2 overlay(dsTots: *next) inz

d i s 2s 0
d j s 2s 0

...

// Total deposit amounts for totals file and report.
j = %lookup(wrkDat: depDats);
if j = 0;
i += 1;
depDats(i) = wrkDat;
j = i;
endif;

if cllNbr < APM_START;
cllTots(j) += depAmt;
else;
apmTots(j) += depAmt;
endif;

...

sorta depDats;

------ END CODE

Sorry if I am making some obvious error here or this is a frequently asked
question. (I've done some searching online.) I've run it in debug,
however, and don't see where I am making a mistake. Any advice or
alternate solution would be appreciated and thanks for your assistance.

Blake