I bought bitspeek but I can not use the MIDI in logic X, the sound just disappears when I select the option MIDI.
How to solve?

Sorry for this very late reply. If you have not figured it out already, the procedure for controlling Bitspeek with MIDI in Logic X is almost the same as for Logic 9. (See http://cdn.soniccharge.com/public/Bitspeek%20User%20Guide.pdf?m=20111007192843))

In short: you need to create a software instrument track for Bitspeek (instead of using Bitspeek as an insert effect on an already existing audio track). It can be found under MIDI-Controlled Effects. See attached screenshot.

Next open the plug-in GUI and select the audio track you want to process with the Side Chain popup at the top.