My sales read outs in Piggy are not representing the actual stats.
At a guess I think this could be due to our use of: http://wordpress.org/extend/plugins/woocommerce-custom-statuses/
(The plugin is recommneded by woothemes)
So with 'woocommerce custom statuses' we created one extra status called 'closed' all sales are set to 'closed' when sale is paid in full, all items have been provided and the invoice receipt has been issued.
So we need Piggy to reflect all sales with the 'closed' status.