[EpiData-list] "find records" not working properly

Hi all, I'm a new user of EpiData, and have a question regarding "finding records." When I try to find a certain case using a "Find Records" command, I sometimes get an error message saying "searching string(s) not found," even though the record I'm looking for is in the file. The identifier field I used is a numeric variable (caseid with four digits). Even more perplexing is for other data files, the "Find Records" works. I've created all data files in a same way, and don't understand why "Find Records" works sometimes, but not other times. Am I missing something or doing in a wrong way? I have a same problem with both EpiData 2.01 and 3.02 versions. Any helps or comments on this will be greatly appreciated. Best,

Jin