ycm go can't jump to declaration

[be thebest]

I used ycm for long time in cpp, it worked well.

Recently i need to use go, so i setup go-completer for ycm.

python install.py --clang-completer --go-completer

it build well.

but when i type F3 in import(which is mapped to gotodefordeclare)

it can't jump. the error msg is: 

ValueError: No JSON object could be decoded

could you help on this?