_IER undefined?


I have a .cpp file that uses IER. When trying to compile it, it gives:

ERROR!   at EOF: [E0300]
1 Assembly Error, No Assembly Warnings
         The following symbols are undefined:

Errors in Source - Assembler Aborted

According to the "TMS320C28x Assembly Language Tools v6.0", section 3.9.5, CPU control registers are predefined, especially IER.

What's going on?

Many thanks for your help,