Thanks Monk. Breakpoints work already. Is the number of line that is not agreed between what mod_perl writes down (fixed #1) and what the Apache::DB tries to understand. The following 4 lines snippet makes it clear:

 1 #!/usr/bin/perl
 2 my $a=2;
 3 print "Content-type: text/plain\n\n";
 4 print "$a\n";
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$my eval is 'evaluated' by mod_perl as:

   
   package ModPerl::ROOT::ModPerl::PerlRun::home_jjmoka_TEST_code_test
+2_2epl;sub handler {local $0 = '/home/jjmoka/TEST/code/test2.pl';
   #line 1 /home/jjmoka/TEST/code/test2.pl
   #!/usr/bin/perl
   my $a=2;
   print "Content-type: text/plain\n\n";
   print "$a\n";
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And that doesn't work. In that case I must fix "#line 1" to "#line 3", and the debugger is able to step each line normally. With any other value X different from 3 "#line X" I see only blank lines on each step. Anyhow 3 is not the solution for every snippet I decide to submit.