Not sure what you mean by "sum worksheets." Do you mean you want to sum every value in the worksheet in to a single cell in worksheet Total?
The Sum command requires you to specify what cells, or range, you need to sum. If you need to sum every cell in multiple worksheets try:
=SUM(Jan:Dec!1:65536)
Assuming that these worksheets and your Total worksheet is located in the same workbook. Let me know if that isn't what you need. HTH.
Re: Question Sum Worksheets(Appended SUM)
If I am clear on what you want:
=SUM('Sheet1'!A1:A4,'Sheet2'!A1:A5)
or
=SUM(Range_Name1,Range_Name2)
You can append ranges in a SUM if you attach each range with a "," the syntax for indicating which sheet the range is on is " 'Sheet1'! " single quote the sheet tab name end with an exclamation mark then indicate the range. If more than one range is used attach each reference with a comma. JSW