[Wannier] Neighbour not found !

[dwz]

Dear Wannier experts :
When wannier90 reads the  overlap matrix file wannier90.mmn file  on my machine , it reports the following info :
 
- -Reading overlaps from wannier90.mmn    : File generated by VASP: MnCH
- -Error reading wannier90.mmn:       3    1    6   0    0  0  0
- -Exiting.......
- -Neighbour not found
 
What "neighbour not found " means ? What I can do to avoid such bug ?
 FYI : the mmn file is written when the SOC turned on. If the SOC switched off, the following procedure reports no bugs. I do not know whether this bug is induced by SOC, seemingly they are irrelevant.
 
Tom Dong
Shandong University , China .
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