make-lemma seem don't work

[jiamo]

Here is the example:

isOdd' : Nat -> Bool
isOdd' Z = ?isOdd'_rhs_1
isOdd' (S k) = ?isOdd'_rhs_2

when you put cursor in isOdd' make-lemma got

isOdd' : Nat -> Bool

isOdd' : Nat -> Bool
isOdd' Z = ?isOdd'_rhs_1
isOdd' (S k) = '_rhs_2

when you put cursor in rhs_2 make-lemma got Errors (0)