Quite often, at conferences or while attending seminars, I will start an interesting discussion with the speaker, first on-site, then later by email, and even though at some point there seems to be some mutual interest, it almost never gives an actual collaboration (i.e. working on an actual paper).
I have no particular problem of working with different people, so I was wondering if it was quite usual to have this huge ratio of "collaboration failure"? In particular, my problem is that, although it's quite simple to have an idea, it seems quite hard to do the next step, that is to actually work with someone you have no connection, and who might even leave in a different country. Are there some techniques to make a "temporary" collaboration work, or at least to detect those which are unlikely to work?