can't use printk in linux 2.4.2 module

Dear All :
I wrote a small module to print "hello world " . when I comiple it under kernel 2.2 , everything works fine.
the output " printk unsolve " appear under 2.4.2 .
with kernel 2.2. , I can find "printk " in the /proc/ksyms , but with kernel 2.4.2 , only "printk_Rsmp" symbol .
Does anyone know how to solve the problem ? Thanks you a lot.