UDF compilation error

Hari

hello guys, I am having trouble in compiling UDFs. the error I get when I try to compile/load an UDF is as follows:

Deleted old libudf\ntx86\2d\libudf.dll

1 file(s) copied. (system "copy C:\Fluent.Inc\fluent6.2.16\src\makefile_nt.udf libudf\ntx86\2d\makefile") 1 file(s) copied. 0 (chdir "libudf")() (chdir "ntx86\2d")() 'nmake' is not recognized as an internal or external command, operable program or batch file. 'nmake' is not recognized as an internal or external command, operable program or batch file.

Done. "x:/fluent tutorials/dynamic_mesh2"

Opening library "libudf"... Error: open_udf_library: The system cannot find the file specified.

Error Object: ()

Can anyone help me in identifying the problem. Thanks