Hello.
Diag Menu is blocked by SPC/MSL code, which is provided by phone's Network provider.
To unlock the phone, please do the next:
1. Install required drivers:
http://octoplusbox.com/files/drivers...Ver_3.12.3.exe,
http://octoplusbox.com/files/drivers...dADBDriver.exe
2. Reflash the phone with "ls990zv4_04.51101" firmware from the Support Area.
3. Perform "Unlock" operation.
Post here result and full Software log of performed operations.