KEIL uVision-5, Segger J-Link Edu EFM8 Flashing Problem

Dear friends,

I need help to identify the reason why I could not flash EFM8LB12F64E (Laser bee, 8051 core) by means of Segger J-Link Edu.

PC : KEIL uVision v5.14.2.1 on Win-10 OS
Board : Custom made board. No problem with Silabs C2 Debugger

.... Project --> Options for Target --> Debug ---> "J-Link / J-Trace EFM8 Driver" SELECTED

.... Project --> Options for Target --> Utilities---> "Use Debug Driver" CHECKED

.... Project --> Options for Target --> Utilities---> "Update Target before Debugging" CHECKED

.... Segger J-Link driver version --> 6.16b

.... Segger J-link functionality --> Checked from command prompt by using jlink commander. The chip EFM8LB12F64E has been erased from command prompt. Jlink can query the EFM8. Following is what I copied from the command prompt screen (Serial number has been replaced by ********* intentionally);

------------------------------------------------------------------
C:\Program Files (x86)\SEGGER\JLink_V616b>jlink
SEGGER J-Link Commander V6.16b (Compiled Jun 9 2017 18:04:04)
DLL version V6.16b, compiled Jun 9 2017 18:03:30

Connecting to J-Link via USB...O.K.
Firmware: J-Link V9 compiled Jun 9 2017 17:27:29
Hardware version: V9.20
S/N: *********
License(s): FlashBP, GDB
OEM: SEGGER-EDU
VTref = 3.270V

Type "connect" to establish a target connection, '?' for help
J-Link>
-------------------------------------------------------------------

I don't see any problem regarding installation, wiring, ... etc. May there be some mismatch between corresponding dll and uVision IDE? dll version is 4.97.11.0 (C:\Keil_v5\C51\BIN\JLinkEFM8.dll)

Also, uVision 5 can connect to MCU in debug mode (ctrl + F5), but, cannot flash it.
Here are the messages in debug mode;
-------------------------------------------------------------------
J-Link info: Device "EFM8LB12F64E" selected.
J-Link info: Device "EFM8LB12F64E" selected.
J-Link info: DevID, DerivID: 0x34, 0x42
J-Link info: Core: CIP-51 (8051 compatible)
J-Link info: Device series: EFM8 series device
J-Link info: CPU supports 4 code breakpoints
J-Link info: Flash infos: 512 byte sectors, 126 sectors
-------------------------------------------------------------------

Can someone help me?

Best regards!