MANOVA  b1 b2 BY a(1,2,3) c(1,2)
/WSFACTORS = b(2)
/WSDESIGN=b
/DESIGN=MWITHIN a(1) MWITHIN a(2) MWITHIN a(3).


我的语法是这样的，要看b在 a三个水平的效应。 这个语法运行报错，提示：

>Error # 12004 in column 24.  Text: 3
>A parenthesized value range in the MANOVA procedure is incorrect or
>incomplete.  The correct syntax requires a pair of integers enclosed in
>parentheses.  Any cases outside of the specified range will not be included in
>the analysis.
>This command not executed.  
若我把 语法中a由三水平，变成两水平，数据不变，可以运行正常。这个是什么原因，望高手指望。
MANOVA  b1 b2 BY a(1,2) c(1,2)/WSFACTORS = b(2)/WSDESIGN=b/DESIGN=MWITHIN a(1) MWITHIN a(2).