no viable initial configuration found: may not find good beam slope

[TamuraJun]

Hello,

This could be a question that has been asked in the list for zillion times but 
I can’t find a good answer from the archive.

I see the subject warning message often when engraving keyboard music with 
cross-staff beaming. I believe that what i need to do is to widen the distance 
between two keyboard staves for a specific system causing the subject warning. 
What is the best way to direct Lilypond to do so? I’d like to keep all the 
default behaviors of staff distance calculation except for the system having 
the subject warning, if possible.

Thanks in advance.

Jun