Need help with encoded message

[JCM_MN]

Hello, not sure if this is something appropriate for this forum but figured it's worth a try. I'm trying to break a coded message for an upcoming trivia contest that was created with three rows of symbols. I've replaced the symbols with letters of the alphabet and get the following three rows of letters:

ABCDEFGHDIEJKLDMNOCNGDFPQ
FGONMRBSSTUBJFPNJVDGBGNMO
NMFWNNSFGEXDIGVMDFBXDIG

(Note: the 'KL' in top row might be one unique letter instead of two)

I've tried several decoding programs including the following:
Monoalphabetic Cipher program and Vigenere Cipher Cracker Tool but don't have the keyword if there is one.

Anybody care to share some ideas of decoding programs to try or other forums that might help?

Thanks in advance,
Jerome