I have a table wih the data of installoations of POS systems. I use another table to summarize the database. In the first column of the summary table I use the function =COUNTIFS(received,">="& $Y7,received,"<="&$Z7) were Received is the range with case receipt date and columns Y and Z contains the datevalue of the first and last day of the week been reported. My problem is that after the six week the formula doesn't work correctly and I can't find why?