OK so some of those letters have got to be vowels and seeing as the letters W, X and K all appear twice I'm pretty certain they're the vowels in your sentence. And seeing as W and X appear next to each other that means we're looking for two vowels together which narrows it down slightly although there are of course still hundreds of possible words that it could be. I'm also pretty sure that it's only broken into groups of two to be more confusing and so it's harder to work out the length of each word.
You've already said you got the idea off Sherlock's website but that it's not the same cipher as any of the ones used on the website, although you did mention I'd find clues on Wikipedia which means the cipher I'm looking for is on there somewhere. If you were on Sherlock's website then you probably noticed, as I did, that there was a link to the Wikipedia page about Ceasar ciphers and although we've already established that it's not a Ceasar cipher, looking at that page more than likely led you to look at and read about other similar ciphers. You also referred to it as a classic cipher which would indicate it has a name. There are several named ciphers listed on Wikipedia and linked from the Ceasar cipher page.
One of the one's I've looked into is called the Vigenere cipher which is a little more complexed and also uses a code word or key. I entertained the possibility that you could have used one of these and have so far tried out several possible code words including Sherlock, Moriarty and the one they've used as their example which is Lemon. I also noticed that the phrase "I Believe In Sherlock" has the same number of letters as your sentence (18), although obviously too many vowels and it didn't work out as your code phrase either, neither did the ones I've mentioned above. I can think of a few more possible code words that you might have used and will probably try them out.
The game continues... 
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