Copy Method Of Worksheet Class Failed ..

I've developed an administrative package in Excel for an After School Care programme. Essentially, there are 57 Child Records. Each record is stored on its own sheet. There are four other sheets in the workbook: three hidden templates, and the front page which holds a summary of all child attendance and balances.

Up until a short time ago, invoices were created from an "Invoices.xlt" file - the program would open the file as a new book, and copy the 1st Template page out until all invoices were created. This worked fine. I've recently changed this so the Invoice template is stored within the main workbook. After I did this, we started having problems.

We can run off up to 25-35 invoices fine (32 at this stage), but eventually it hits a point where the Activesheet.Copy command fails. After this point it is impossible to copy further sheets. I CAN, however, use Insert -> Worksheet. It is only the copy function that fails.

Because it's such a strange problem, I've uploaded an example with children's names changed. It can be found on [url]

The steps to recreate the problem are simple: Open the file, select all of the children's names (from Child to Child z), and click the "Create Invoices" button at the top.