problem installing MongoDB

[Johan Ismael]

Hi,

After typing sudo port install mongodb in the terminal, here is the  
Error message I receive :

Error: Target org.macports.activate returned: Image error: /opt/local/ 
bin/xmlwf already exists and does not belong to a registered port.   
Unable to activate port expat. Use 'port -f activate expat' to force  
the activation.
Log for expat is at: /opt/local/var/macports/logs/ 
_opt_local_var_macports_sources_rsync 
.macports.org_release_ports_textproc_expat/main.log
Error: The following dependencies failed to build: boost expat zlib  
libpcap pcre readline ncurses ncursesw scons python26 db46 gdbm  
gettext libiconv gperf openssl sqlite3 spidermonkey nspr
Error: Status 1 encountered during processing.


Any idea what's going wrong ?

Thanks