cache_get() not working properly due to a possible prefix problem

I just installed the memcache module and most things appear to be faster now that they are coming from cache. There are a few pieces of data that I would expect to come from the cache but are not. If I use memcache.db.in the values will at least pull from the database but ideally I'd like to use memcache.inc for better performance.

I set my data using the following function:

  cache_set('yt_city_links_59', $myarray, 'cache', time()+(60*60*24)); // cache for 1 day

I then read the data out using the following:

  $cache = cache_get('yt_city_links_59', 'cache');

This was all working fine until I tried using memcache.inc to increase performance. Here is a screenshot from the output of the memcache_admin module:

You'll notice that the yt_city_links_59 is a miss since it doesn't have a 1 next to it. I've tried a bunch on my own trying to get this value to be a hit instead of a miss but for some reason it never works. I noticed that there are some differences with the prefixing of the variables at times. For example, my yt_city_links_59 key is prefixed with 'yt_prod-cache-' but all the other values in the screenshot are prefixed with 'yt_prod-cache_'. It appears that for some reason the prefix is followed by an underscore in some cases and by a hyphen in other cases. I suspect that this could be a problem but I'm not sure.

I suspect that the reason memcache.db.inc is working is because it's falling back to the database table if the value can't be found in memcache.

Any help is greatly appreciated.