I'm trying to use my trombone recorded in audio, then converted to a midi file in melodyne, then the midi file dragged into a synth track, the clip converted to a groove clip, and voila, a bass part or flute part, etc. However, when i do that, the tempi are not aligned with my project. What am i doing wrong?

Hold [shift] (or [ctrl] I can never remember which) when you drag it to keep the time aligned.

One easy way to approach this by changing your Snap settings in the Snap module from "Snap to" to "Snap by." The module is typically located somewhere in the top left of your screen. After that, change the Snap Resolution to a whole note. This way when you are dragging MIDI clips around, you know that the relative positions will be preserved.
 I can't post links yet, but if you google "sonar snap module," you should be able to figure it out.
 
Also, I don't know what your project is like but you probably don't have to convert the MIDI clips to groove clips. Hope this helps.

Thanks for the replies. I'm still getting no cigar. Here's what I've tried:
 
1) play bass part in audio with trombone at slow tempo; open track in melodyne; save as midi file; remove audio file I had made; open up bass synth instrument; paste midi file in track; adjust octaves, move tempo to corret speed; open up clips in pro channel; set loop to on, and tried to correct original tempo and beats; would let me;tempi wrong with original drum track
 
2) same as above, but made audio and conversion in a separate project, made grooveclip, copied, and closed that, opened up original project, and pasted. Same result. 
 
I SHOULD be able to do this, and make a MIDI clip I can paste at a tempo that follows the project, no?

Just to follow up on the suggestion that groove clipping might not be necessary, I recorded material at the speed of the project, opened melodyne, save the audio as a midi, all at the same tempo. I played the midi file with windows media player. All fine. I dragged the file into my project......... time completely wacky, about 3.5 times faster than the original. After 3 hours of trial and error, reading the manuals, etc., I'm at a losss, and as you may imagine, a wee bit frustrated. Will appreciate advice. Wife is keeping me away from coffee and sharp objects.
 
Melodyne seems to be doing it's job. What's going on with Sonar here?
 

1) Record trombone.
2) Drag over the audio to create a selection
3) Right click | Region FX | Create Region FX | Medlodyne
4) Selected area turns green,  Melodyne opens (you can ignore it)
5) Drag the green selection from the trombone track to a midi track,  midi is inserted.
 
You do not need to save or load or copy/paste any midi files...
 
Here's a video  (not mine)
 

YAY!!! Hooray for Karyn!!!! Thank YOU!!!!!

You're welcome.