[Dev-C++] A question about acmDriverAdd and acmDriverRemove APIs

Hello,
I need to use the audio compression manager and add a custom
compressor to it using the acmDriverAdd() API. I've included the
msacm.h header file in my project and specified to the linker to use
the "libmsacm32.a" library file throught the project option dialogs.
In my project I also use others ACM APIs such as acmDriverOpen(),
acmDriverClose() etc...
The matter is the linking step:

[Linker error] undefined reference to `acmDriverAdd'
[Linker error] undefined reference to `acmDriverRemove'

Using a hexadecimal editor I've taked a look in the "libmsacm32.a"
file and there are the definitions for acmDriverAdd and
acmDriverRemove (with or without UNICODE support). What's wrong?

Thank you,
--
Gaetano Sferra

PS: I've already tryed to put an '_' or "__" before the function names
but it's not useful, the same errors occurs.