I cannot swith to chinese input by ctrl_space on debian, what's wrong ?

idaii

I used MEPIS_linux (based on debian), everything is good, but when I installed SCIM by: apt-get install scim scim-chinese from "deb http://debian.ustc.edu.cn/....", then
# export XMODIFIERS=@im=SCIM, XIM=SCIM
# scim -d

but, on kde, I cannot switch to chinese input mode by control_space.

To james_su, what's wrong with my Linux ?