Some midi notes dont play

So Im listening to a midi track, say playing d pro, and I have 4 notes in the midi track, all look normal in PRV, but as I listen to it as I watch, say only 3 play and one is silent. If I do it numerous times, the note or notes that dont play are not always the same notes. Like sometimes 1 2 and 3 will play, and not 4, but later 1 2 and 4 will play, but not 3. If I bounce the track, all four are in the audio recording, but if Im trying to check it out before bouncing I cant hear them all at the same time. ? ? thanks, treesha

Thanks Zargg, my setting was at 250 so I will see what happens after putting it to 500. Done with that song now so hopefully the 500 will prevent this next time. treesha

Had a chance to work with midi in a new song with the setting at 500 and the playback was good, all the notes played. Thanks again