>update on the problem: i guess some of the records have somehow affected the field paystart and not sure how it happened. when i deleted some records, it began to produce the correct results expected and its working now. Its just i wasn't able to find out what really went wrong and how those records ive deleted have affected the results
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>Thanks for your suggestions

You could always take a look at those deleted records for clues to what was going on (assuming that we're talking about DBF files).