2664 works for different sellers at different times of the month. It seems to run on a 30 day cycle. If you where able to access the offer last month on the tenth, with a starting date on the 13th, I would expect you would have a chance of accessing the offer on the 9th this month, with a start date on the 12th. ( March having 31 days the offer begins a day earlier in April )
My guess is that sellers who recieve the "offer expired" message are in a part of the cycle when the offer is not valid for them. This period will be around 17 days as the 30 day cycle includes a period of around 3 days over which the offer can be accepted prior to the selling period, ten days of selling period and 17 days of "offer expired".
Most of the above I am pretty certian of. The following is more speculative.
Experience from others on the forums show that not everyone recieves the offer regularly. Just a guess here, but I suspect ebay have a base line of criteria used to select sellers who are valid for the offer each month. This base line may vary depending on how ebay the company is performing and individual sellers may fall above the base line criteria some months and below other months depending on their individual sales. Other sellers excede the base line criteria most months and so recieve the offer on a pretty regular basis.
Ebay could be using this offer to manage listing numbers from non store sellers on the total ebay Australia site, to meet certian pre-determined levels each month. Less non store listings on the site, could result in the base line criteria being lowered and more people having access to the offer that month.
Thanks for sharing anyway, it is always worth a try 
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