Windows 7 : device is visible but connection failed

I tried it on the linux box from Chromium. Result is slightly different. All the time different. Here is the transcript of several connexions:

No code in storage.
>>> Connecting...
Set Slow Write = true
>>> Connecting to Puck.js c064
BT> Device Name: Puck.js c064
BT> Device ID: t5VB7pAhtyVVCJlk1naOMQ==
BT> ERROR: NetworkError: Connection failed for unknown reason.
ERROR: [notify_error] Connection Failed.
>>> Connection Failed.
>>> Connecting...
Set Slow Write = true
>>> Connecting to Puck.js c064
BT> Device Name: Puck.js c064
BT> Device ID: t5VB7pAhtyVVCJlk1naOMQ==
>>> Connected to BLE
BT> Connected
BT> Disconnected (gattserverdisconnected)
ERROR: [notify_error] Connection Failed.
>>> Connection Failed.
ERROR: [notify_error] Connection Failed.
>>> Connection Failed.
>>> Connecting...
Set Slow Write = true
>>> Connecting to Puck.js c064
BT> Device Name: Puck.js c064
BT> Device ID: t5VB7pAhtyVVCJlk1naOMQ==
>>> Connected to BLE
BT> Connected
BT> Disconnected (gattserverdisconnected)
ERROR: [notify_error] Connection Failed.
>>> Connection Failed.
ERROR: [notify_error] Connection Failed.
>>> Connection Failed.
>>> Connecting...
Set Slow Write = true
>>> Connecting to Puck.js c064
BT> Device Name: Puck.js c064
BT> Device ID: t5VB7pAhtyVVCJlk1naOMQ==
>>> Connected to BLE
BT> Connected
Got ""
No Prompt found, got undefined - issuing Ctrl-C to try and break out
Got ""
No Prompt found, got undefined - issuing Ctrl-C to try and break out
Got ""
No Prompt found, got undefined - issuing Ctrl-C to try and break out
Got ""
No Prompt found, got undefined - issuing Ctrl-C to try and break out
Got ""
No Prompt found, got undefined - issuing Ctrl-C to try and break out