I can;t check the attachments from the first post, for some reason they don;t always appear for me,
How are you creating the shipping calculation ?
What I would do is open the ecart object, go to the shipping tab, and create a new calculation.
Then my trigger would be
Total number of items > 0 AND SubTotal of items <12
create a flat rate shipping of 2.95
(make sure you put the updated ecart file on the testing server)