The problem is that - as someone remarked earlier - there just isn't that much ACMI work out there at the moment, so it's really hard to make a case for investing the necessary cost and time in an AOC, at least for this aircraft type. Despite Flightline closing down just under a year ago, Transwede (RJ70/85 ACMI operator) has recently announced they'll be getting out of the business too. A couple of southern European F100 operators are still providing relatively low-cost 100-seat lift, but there's just not much call for 146/RJ ACMI operations at the moment. The main niches where the aircraft could excel are difficult airfields (Scatsta, LCY) and no-one's looking for extra capacity there
AFAIK. Plus also, the shift in sterling vs the euro over the last couple of years has meant that UK operators are a lot more competitive in the Euro zone and conversely Euro ACMI operators are less interesting to UK airlines. It's a shame, because Nex has worked very hard to get going and keep going.