You don't really say what the error is or what you expect, so I'm just making a guess here.

select a
scan for !deleted()
   m.lcA = a.Data
   select b
   scan for b.data = m.lcA      <----  Just guessing, but I think an .m here will take care of it
   *  scan for data = a.Data    <------ Above line could be changed to this, then you don't need m.lcA = a.Data
      store something
   endscan
   *  select a    <-- not needed, a will be automatically selected
endscan

>I haven't been successful in employing nested scans,
>
>select a
>scan for !deleted()
>m.lcA = a.Data
>select b
>scan for b.data = lcA
>store something
>endscan
>select a
>endscan
>
>As you can see this doesn't work the way I expect. It seems to "skip" or "Ignore" records.
>
>Any thoughts are greatly appreciated.
>
>GSD