Hi
I've had similar problems and it took months to find a solution.....the leetro cards seem to be a "bit " cranky and after months of searching I found the post below. Its easy to miss but you need to visit the Chinese leetro site
http://leetro.com/leetro_web_page/first.asp......yea all is in Chinese but follow the directions.
Go to the 4th menu at the top and click the first subcategory, you'll find the page with the downloads.. You need to reinstall the firmware first before hooking your lazer up via USB. Check out the manuals in English for directions on loading drivers as well as getting the software to respond. What Cutting software was supplied with your machine?If LazerCut you need to choose the controler card.
(I've fixed our problem by converting back to the .14 firmware version.
You can get all the firmwares in the lasercut 5.3 pack that you find on the CHINESE version of the leetro website http://leetro.com/leetro_web_page/first.asp
Go to the 4th menu at the top and click the first subcategory, you'll find the page with the downloads.
Hope it helps. )