hi guys. i am a bit new at this but i need help.
when i put an effect in the track effects bin on a soft synth track, half the notes go missing.
even when i created a bus and put the effect there, the same thing happened. the master as well.
if i disable the effect, i have all my notes back!!!!!!!???????
i dont know what im doing wrong.
please help.
Thanks

What effect is it? 
 
I would change the title to a descriptive one of the problem.  Perhaps this "notes disappear when an effect is inserted".   
 
You will get a better response because members will know that its about.
 
And a big welcome to the forum. 

Welcome to the forum!
What do you mean by soft synth track? A simple instrument track, the MIDI track of a MIDI/audio pair or the audio output track of a MIDI/audio pair?
Are you perhaps putting a MIDI FX on an audio track or an audio FX on a MIDI track?
Do the notes actually disappear from the grid, or are they just skipped during playback? If skipping is the problem, double the buffer size in "MIDI buffers, prepare using xx ms buffer".
Otherwise, a little more info is necessary.

Edit/Preferences->MIDI->Playback and Recording
 
Under [Playback]
Prepare using [500] Millisecond Buffers
 
Experiment with values upward of 500 to 1000.