@kilroy and all others, don't use the mt4 plugin from marketcalls.
That one doesn't work correctly.
Use the one from the Amibroker yahoo list
h ttp://finance.groups.yahoo.com/group/amibroker/
It can be found in the files section and file name is ami mt4 plugin.zip
This is the direct download link(if the link doesn't work then go to the files section)
h ttp://f1.grp.yahoofs.com/v1/wC9WUJ2z9lkQ6hQqn94rb56O9gepp65-aCCP2bZu8O2wJdlxZsVqo_K-rBDo-ZnzlVWWQZ80VhUKfAQeYJyre0laqw1BNQ/ami%20mt4%20plugin.zip
data_count is the number of bars to backfill at once. So if you need to backfill 2000 bars and if you have set data-count to 500 then it will load 4 * 500 bars. If you have set to 1000 then it will load two times ... 2 * 1000 and so on.
If backfill is finished then you should choose a lower data-count like 50 or 10.
Don't understand you first sentence. So if someone could please translate it then I could probably answer to it.