Sounds like you are trying to add several sheets using the same reference. Once you add a sheet using Before or After, you cannot trust the reference to properly point to the same sheet. You will need to close that reference and create a new one to correctly point to the new layout.
Here is a VI that I wrote for this purpose. I use it to setup a workbook with a specific number of sheets, each with a specific name. Just put it in a for loop with an array of the desired sheet names. You can also place it in your current loop, to select the next sheet before writing.
Michael Munroe
www.abcdefirm.com
