%SUBARR compile error

My first attempt using %SUBARR:
I get *RNF5343 errors on lines that update the variable
used as an index, but lines that use %SUBARR to copy
values between arrays are not flagged ?

<snip>
* Start: data to break a field into left and right parts -----------------
D bfMaxC C 20 max break fld chars
D bfMax S 5I 0 DIM(bfMaxC) " " " "
D bf@ S 5I 0 bf# index
D bf# S 1A DIM(bfMaxC) break fld array
D bfEle S 5I 0 bf# element count
*
D bc_DS DS
D bc1_3 1 3A break chars 1-3
D bc1_2 1 2A " " 1-2
D bc1 1 1A " char 1
D bc2 2 2A " " 2
D bc3 3 3A " " 3
*
D DS
D BrkFldLt 1 20A
D BrkFldLt# 1 20A DIM(bfMaxC)
D BrkFldLt9 1 20S 0
*
D DS
D BrkFldRt 1 20A
D BrkFldRt# 1 20A DIM(bfMaxC)
D BrkFldRt9 1 20S 0
* End : data to break a field into left and right parts -----------------
<snip>

<snip>
//Start: loop to break field into left and right parts ----------------
Dow (bf@ <= bfMax); <- *RNF5343 ???
Select;
When bc3 > *blank;
If bf#(bf@) = bc1 And
bf#(bf@ + 1) = bc2 And
bf#(bf@ + 2) = bc3;
If bf@ > 3;
EvalR BrkFldLt# = %Subarr(bf#: 1: bf@ - 3); <- why no error here ?
Else;
EvalR BrkFldLt = '0';
Endif;
bfEle = (bfMax - (bf@ + 3));
EvalR BrkFldRt# = %Subarr(bf#: bf@ + 3: bfEle);
Leave; // exit loop
Endif;
<snip>