Some wont work
These
https://lmms.io/wiki/index.php?title=Tested_VSTs
will
I always recommend the stunningly good Synth1 as kind of 'proff of concept'
I have written some about that in the wiki here:
https://lmms.io/wiki/index.php?title=1. ... _with_VSTs
If you go trough these guide-lines, and still have problems after that, do post again