Cannot npm install with indicated registry in ubuntu with nodejs v6.9.5

[Dat Banh]

Hi guys,
Please help me to check
When I indicate a registry during npm install, it failed. However, it successful if I indicate default registry

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# npm install grunt-cli -registry="http://nexus.wdf.sap.corp:8081/nexus/content/groups/build.milestones.npm"
npm ERR! Linux 4.4.74-92.29-default
npm ERR! argv "/opt/node-v6.9.5-linux-x64/bin/node" "/usr/bin/npm" "install" "grunt-cli" "-registry=http://nexus.wdf.sap.corp:8081/nexus/content/groups/build.milestones.npm"
npm ERR! node v6.9.5
npm ERR! npm v3.10.10

npm ERR! Cannot convert undefined or null to object
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR! <https://github.com/npm/npm/issues>

npm ERR! Please include the following file with any support request:
npm ERR! /opt/npm-debug.log

----------------------
npm install grunt -registry="http://registry.npmjs.org"
opt
`-- grunt@1.0.1
  +-- coffee-script@1.10.0
  +-- dateformat@1.0.12
  | +-- get-stdin@4.0.1
  | `-- meow@3.7.0
  | +-- camelcase-keys@2.1.0
  | | `-- camelcase@2.1.1
  | +-- decamelize@1.2.0
  | +-- loud-rejection@1.6.0
  | | +-- currently-unhandled@0.4.1

----------------------
Ubutun info
# cat /etc/*release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=12.04
DISTRIB_CODENAME=precise
DISTRIB_DESCRIPTION="Ubuntu 12.04.5 LTS"
NAME="Ubuntu"
VERSION="12.04.5 LTS, Precise Pangolin"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu precise (12.04.5 LTS)"
VERSION_ID="12.04"

Best regards,
Dat