My understanding is, and I'm sure someone will tell me if I'm incorrect.....
a .nri file is not needed for the macro to function. .nri stands for "Nothing Real Icon" ... Nothing Real is the company that orginally created Shake.
... anyways, the .nri file makes the macro look pretty inside of shake, but has nothing to do with the functionality of it.
There is probabbly no "@" symbol listed in the macroname.h file or the macronameUI.h file.
Go back into the Shake manual and read where it talks about the "@" symbol. If you do not have a .nri file for your macro, then that "@" symbol needs to be in the code for the macro.