no line 200 in file.for

Hi
I compiled a source with 
g77 version 2.95.3 20010315 (SuSE) (from FSF-g77 version 0.5.25 20010315 
(release)
with the switch -ggdb3. When I try to debug it with GNU gdb 5.1.1 configured 
as "i386-suse-linux" I get the following behaviour:
I can list my source like 

 list nlswe2d.for:298
293     *     
294              call time_step(nodi,ntr,ib,tni,mxtr,nc,mxnn,np,ibct,bct,
295          +        dti,angl,xmin,ymin,ymax,dx,dy,
296          +        uxn,uyn,dn,time,h,coorn,ndim,riem,ir,dt)
297     *     
298     *     Fractorial Step
299     *     Primo passo S(H(u))
300     *     
301              call Homo_step(n,nodi,ntr,ib,tni,mxtr,nc,mxnn,np,ibct,bct,
302          +        dti,angl,xmin,ymin,ymax,dx,dy,time,h,coorn,ndim,ifondo,

I get info like

info source
Current source file is nlswe2d.for
Compilation directory is /home/robber/nlswe/nlswe2d
Located in /home/robber/nlswe/nlswe2d/nlswe2d.for
Contains 1070 lines.
Source language is fortran.
Compiled with DWARF 2 debugging format.

but i cannot put in any way a brekpoint in my source I receive the following 
answer:

b nlswe2d.for:200

No line 200 in file "nlswe2d.for"

this behavior appears only in some excutables although I make them all with 
the same makefile.


-- 
-----------------------------------------------------------------------              
Roberto Bernetti                             e-mail: [email protected]           
V. S.da Vecchia del Pinocchio 1/A          
60131 ANCONA 
tel/fax 071 2867103