[ns] make problems in ns2.1b7

[Pavan Verma <csu97136@cse.iitd.ernet.in>]

I am using ns2.1b7

I wrote a little code for a new agent.. 
and I'm getting this error when I make.. saying..

tclAppInit.o: In function `Tcl_AppInit':
tclAppInit.o(.text+0x11a): undefined reference to `et_ns_ptypes'

any idea why this is happening ??

- Pavan