Perhaps this table will help to clarify how the various modes and keys inter-relate (Hope I've got the HTML right!)
Key Signature Major Dorian Phrygian Lydian Mixolydian Minor Locrian Sharps 7 C# D# E# F# G# A# B# 6 F# G# A# B C# D# E# 5 B C# D# E F# G# A# 4 E F# G# A B C# D# 3 A B C# D E F# G# 2 D E F# G A B C# 1 G A B C D E F# 0 C D E F G A B Flats 1 F G A Bb C D E 2 Bb C D Eb F G A 3 Eb F G Ab Bb C D 4 Ab Bb C Db Eb F G 5 Db Eb F Gb Ab Bb C 6 Gb Ab Bb Cb Db Eb F 7 Cb Db Eb Fb Gb Ab Bb Wassail! V