quarter note triplets just don't want to behave properly

[Chip]

I am having a heck of a time with quarter note triplets. 1/8th note 
triplets work fine. Here is the code I am using -
\times 2/3 {r4 cs'[ cs] cs[ c b]}

Just for comparison sake I have this code for 1/8th note which works fine -
\times 2/3 {r8[ as^\markup {Ritard} as] as[ as as] as[ as as] as[ as as]}

What am I doing wrong with the 1/4 note triplets?
--
Chip