Automatic syphon

Hi all first post here so Im hoping someone out there can help Im at a total loss I just fitted an auto syphon but once it flushes it just keeps going ie: the water keeps flowing I have changed it twice with the same problem any ideas ???

I'm familiar with auto siphons used for racking homemade wine and beer, but I've never heard of an automatic siphon for a toilet. The toilet bowl creates it's own siphon when enough water flows into it to fill the discharge channel.

Can you post a link to the manufacturer's web page showing your automatic siphon so that we can take a look at it and see how it's supposed to work?

I think this might be the one http://www.masefield-epson.co.uk/plumbing-products/bbs-automatic-syphons-and-accessories.html They are used in every mens toilet but as far as I can make out this is the only company that makes them