A problem debugging libraries

I'm writing software using libraries liboctave, LAPACK, and BLAS.
I added function dnrm2alt1 to blas and changed lapack to use that 
instead of dnrm2. When I try to debug a program using blas "break 
dnrm2_" works in gdb but "break dnrm2alt1_" does not. Gdb can't find 
function dnrm2alt1_. Can anybody tell what is wrong?

Here are outputs of some commands:

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tohoyn@tohoyn-laptop:~/tyo/omat/aallokkeet/libinterp3d1$ 
update-alternatives --config libblas.so.3
There are 2 choices for the alternative libblas.so.3 (providing 
/usr/lib/libblas.so.3).

   Selection    Path                                    Priority   Status
------------------------------------------------------------
   0            /usr/lib/atlas-base/atlas/libblas.so.3   35        auto mode
   1            /usr/lib/atlas-base/atlas/libblas.so.3   35 
manual mode
* 2            /usr/lib/libblas/libblas.so.3            10        manual 
mode

Press enter to keep the current choice[*], or type selection number:
tohoyn@tohoyn-laptop:~/tyo/omat/aallokkeet/libinterp3d1$
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tohoyn@tohoyn-laptop:~/tyo/omat/aallokkeet/libinterp3d1$ 
update-alternatives --config liblapack.so.3
There are 2 choices for the alternative liblapack.so.3 (providing 
/usr/lib/liblapack.so.3).

   Selection    Path                                      Priority   Status
------------------------------------------------------------
* 0            /usr/lib/lapack/liblapack.so.3             10        auto 
mode
   1            /usr/lib/atlas-base/atlas/liblapack.so.3   5 
manual mode
   2            /usr/lib/lapack/liblapack.so.3             10 
manual mode

Press enter to keep the current choice[*], or type selection number:
tohoyn@tohoyn-laptop:~/tyo/omat/aallokkeet/libinterp3d1$
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tohoyn@tohoyn-laptop:/usr/lib/libblas$ objdump -T libblas.so.3.0 | grep 
-i dnrm2
0000000000040320 g    DF .text	0000000000000011  Base        dnrm2sub_
000000000000fd50 g    DF .text	000000000000002b  Base        cblas_dnrm2
0000000000040220 g    DF .text	000000000000006b  Base        dnrm2_
0000000000040290 g    DF .text	0000000000000084  Base        dnrm2alt1_
tohoyn@tohoyn-laptop:/usr/lib/libblas$
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tohoyn@tohoyn-laptop:/usr/lib/lapack$ objdump -T liblapack.so.3.0 | grep 
-i dnrm2
0000000000000000      DF *UND*	0000000000000000              dnrm2alt1_
tohoyn@tohoyn-laptop:/usr/lib/lapack$
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      - Tommi H.