Trouble compiling module

I created a kernel module for the 2.6.33 kernel outside the kernel source directory . When i give the make command it says

Code:

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Nothing to be done for /root/mydrivers

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Here's my makefile

Code:

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obj-m=mydriver.o
modules :
        make -C ../kerndev/linux-2.6/M=$(PWD) modules
clean:
        make -C ../kerndev/linux-2.6/M=$(PWD) clean

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my module source is in /root/mydrivers and the kernel source in /root/kerndev/linux-2.6