Schemeでcall of non-procedure: #<unspecified>というエラーが出る

Schemeで次のプログラムを動かしています(実行結果　https://ideone.com/FYC14X)。

Scheme
1(define dfs
2  (lambda (depth x y z length)
3    ((if
4      (and  (<= (abs x) 1) (<= (abs y) 1) (<= (abs z) 1) (<= depth 2))
5      (do ((i -1 (+ i 1))) ((> i 1))
6        (do ((j -1 (+ j 1)))((> j 1))
7          (do ((k -1 (+ k 1)))((> k 1))
8            (if
9             (not (and (= i 0)(= j 0)(= k 0)))
10             (print i " " j " " k)
11             ))))))))
12 
13 
14 
15(do ((i -1 (+ i 1))) ((> i 1))
16  (do ((j -1 (+ j 1)))((> j 1))
17    (do ((k -1 (+ k 1)))((> k 1))
18      (if
19       (= 1 (+ (abs i) (abs j) (abs k)))
20       (dfs 1 (/ i 3) (/ j 3) (/ k 3) (/ 3))))))
21                                        ;    )
22 
23 
24(exit)

ですが見たことのないエラーが出て困っています。詳しい方助けてください。次の質問と回答を参考にコードを書きました（https://teratail.com/questions/141999）

log
1Error: call of non-procedure: #<unspecified>
2
3	Call history:
4
5	<eval>	  [dfs] (print i " " j " " k)
6	<eval>	  [dfs] (doloop15 (+ k 1))
7	<eval>	  [dfs] (+ k 1)
8	<eval>	  [dfs] (> k 1)
9	<eval>	  [dfs] (not (and (= i 0) (= j 0) (= k 0)))
10	<eval>	  [dfs] (= i 0)
11	<eval>	  [dfs] (print i " " j " " k)
12	<eval>	  [dfs] (doloop15 (+ k 1))
13	<eval>	  [dfs] (+ k 1)
14	<eval>	  [dfs] (> k 1)
15	<eval>	  [dfs] (doloop12 (+ j 1))
16	<eval>	  [dfs] (+ j 1)
17	<eval>	  [dfs] (> j 1)
18	<eval>	  [dfs] (doloop9 (+ i 1))
19	<eval>	  [dfs] (+ i 1)
20	<eval>	  [dfs] (> i 1)	<--