Changing starting invoice number

[Pablo Francesca]

I would like to change my starting invoice number.  I remember reading about this before, but I can't seem to find the information anymore.  When I try to edit the xml file for my gnucash 2.2.9, I first decompressed it using Jzip, then edited it with Notepad+++.  Near the beginning of the file in the counters section, I found a value of 123 under Invoices and I changed it to 2126.  Then I saved and recompressed the file and changed the file extension. When I tried to open it with gnucash I get the dreaded cannot parse file message.

When I create a new invoice currently, the invoice number is 000124, so
I'm pretty sure this is the correct area to edit.  I would like the
invoice number to start at 002126.

What did I miss?