When ending any relationship, always leave the door open for new business down the road. Simply because something doesn't work now doesn't necessarily mean that it won't work in the future. This is even more important when you're testing emerging media. For example, I'm a firm believer that mobile advertising can work for financial direct response advertisers. I have this belief despite the fact that mobile has yet to work for us in the few tests we've done. In fact, not only didn't these tests work, but the performance was downright dismal. While it was obvious to all involved that the advertising relationship couldn't continue, I made it a point to keep the door open for another test in the future.

Technology changes, publisher audience composition changes, agencies and vendors improve their skills. Also, your own experience and skill set continues to improve. Keeping your options open to re-test options that don't currently work can be a goldmine for you in the future. I've had numerous times where skills, newly acquired knowledge or technology have helped my team, and I've turned a failed campaign into a clear-cut winner. Of course, I never would have had the opportunity to find this out if I closed the possibility of another test at the time the campaign failed.

Another area where keeping the door open is desirable is when you switch agencies or service vendors. You never know if the grass is going to be greener with a new agency or vendor, so keeping the option open to return is preferred. I recently shifted to a new company for our third-party ad serving. I wasn't unhappy with my previous vendor of several years, but several factors including better technology fits with other new vendors played a big role in my switch. While I anticipate my new vendor relationship will prosper, I don't possess a crystal ball and therefore wanted to make sure that I kept the split with my former vendor very amicable.