install SQL Server 2016 in System Context failed if PolyBase feature is enabled

When tried installing SQl Server Enterprise Edition 2016 SP2 with configuration File, it failed with exception. 
It appears only when "PolyBase" Feature is enabled in System Context.

In Detail.txt it shows below error:

(01) 2019-06-17 10:25:50 SQLPolyBase: : ExecuteScriptStatement completed.
(01) 2019-06-17 10:25:50 SQLPolyBase: --PolybaseDatabaseConfig: Reading Cluster\ConfigureAccess.Polybase.sql...
(01) 2019-06-17 10:25:50 SQLPolyBase: --PolybaseDatabaseConfig: Replacing $(EngineServiceAccount) with NT AUTHORITY\NETWORK SERVICE...
(01) 2019-06-17 10:25:50 SQLPolyBase: --PolybaseDatabaseConfig: Replacing $(DmsServiceAccount) with NT AUTHORITY\NETWORK SERVICE...
(01) 2019-06-17 10:25:50 SQLPolyBase: --PolybaseDatabaseConfig: Replacing $(Admin) with WORKGROUP\SYSTEM...
....
(01) 2019-06-17 10:25:50 Slp: Exception type: Microsoft.SqlServer.Configuration.Sco.ScoException
(01) 2019-06-17 10:25:50 Slp:     Message: 
(01) 2019-06-17 10:25:50 Slp:         Cannot find the principal 'WORKGROUP\SYSTEM', because it does not exist or you do not have permission
(01) 2019-06-17 10:25:50 Slp:         Changed database context to 'DWQueue'
(01) 2019-06-17 10:25:50 Slp:     HResult : 0x84bb0001
(01) 2019-06-17 10:25:50 Slp:         FacilityCode : 1211 (4bb)
(01) 2019-06-17 10:25:50 Slp:         ErrorCode : 1 (0001)

The problem is it takes admin account as 'WORKGROUP\SYSTEM' instead of 'NT AUTHORITY\SYSTEM'.

Please Help me out !!!

Regards,

Alex