Problem with GNAT option "-gnatt" (adt tree)

[dev-abf@wanadoo.fr (Alain FONTAINE)]

I am tryng to use "adabrowse" for making an html documentation
for a piece of software.
My environment is GNAT 3.14+ASIS 3.14+adbrowse on windows XP

The problem is the following:

The spec files compiled with the option "-gnatt" as:
    gcc -c -gnatc -gnatt -gnatQ -gnatq file.ads

either produce an .adt file or
don't produce adt file with the following message:
'linker input file unused since linking not done'

Example:
D:\dev\ada\adabrowse_2.01\de>gcc -c -gnatc -gnatt -gnatQ -gnatq -I.. f1.ads

D:\dev\ada\adabrowse_2.01\de>gcc -c -gnatc -gnatt -gnatQ -gnatq -I.. f2.ADS
gcc: f2.ADS: linker input file unused since linking not done

I have not found something sound for this message.

As I need the adt file for adabrowse I am stuck!
Remarks: 
1)The software compiles fine and can produce an executable,
so there is no compilation error and linkage is done.
2) adabrowse is working fine on the example

Can somebody explain the problem?
Thank you in advance