Just tested joining two clips/converting/exporting.
It works but when going to move the clips to the bin it results full (is completely empty) and needing to eliminate the files bypassing the bin
Don't know if because the installation I did; if the problem continues I will remove all packages and start again following the procedure you suggested to me
Edit (May 21,2015)
@ Djemos: - Due the bin's issue I have been removing mlt>libcdio-paranoia>Kdenlive and reinstalling following that hint of yours (with the command "slapt-src -i mlt" can't create it, so I have been installing "mlt" and requested dependencies by packages from Repository Slacky.eu and something by SlackBuild and source).
Final result: Kdenlive works properly ( as before

) but the bin is still faulty, can't use it, needing to eliminate files with direct command.
The folder /home/dominum/.local/share/Trash is empty, don't know how to fix it.
>>> jack-audio-connection-kit-0.124.1-i486-1_SBo and ladspa_sdk-1.13-i486-4_SBo have been upgraded by Gslapt.
Cheers!
Edit (May 24,2015)
Solved
cd /home/user/.local/share/Trash/
# rm -fr *
Start new session or reboot