I removed the amule from wollstreckernet, and installed the one from dapper backport, this is the result:
luca@luca:~$ amule
amule: Symbol `_ZTI7wxSizer' has different size in shared object, consider re-linking
Fatal Error: Mismatch between the program and library build versions detected.
The library used 2.6 (no debug,Unicode,compiler with C++ ABI 102,wx containers,compatible with 2.4),
and your program used 2.6 (no debug,Unicode,compiler with C++ ABI 1002,wx containers,compatible with 2.4).
Aborted
Probably the problem is Wx library, I have installed 2.6.3.2-2. But not from ubuntu repos, because for dapper there isn't that version of wx. The only avalaible is 2.6.1 and with that version on my linux box amule crashes every 15 minutes.