Missing Keys/Crystal Reports

Hi
I've got a user of my app who has a strange problem with Crystal reports
not finding some records in a table. I've seen the table in question,
and i can search on the key using an infopower lookupcombo no problem,
but if i use crystal to set up a selection criteria on this key, it
doesn't find it, but it does appear in list reports in its correct
position.
Im using D1, dBase files, BDE 2.52.
Anyone come across this before?
Thanks
Wes Kinzett