Project Launcher Server Build Error : Couldn't Find Rules

Hello everyone! I’ve been trying to figure out why I can’t build my server when I use project launcher. It will let me build a default client but it won’t let me build a Window’s Server. I get the following error message. Any ideas? I already tried some of the suggestions on some other posts but didn’t work for me.

Couldn’t find target rules file for target ‘UE4Server’ in rules assembly ‘UE4Rules, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null’.
Location: C:\Program Files\Epic Games\UE_4.21\Engine\Intermediate\Build\BuildRules\UE4Rules.dll
Target rules found:

     (see C:\Users\Yas\AppData\Roaming\Unreal Engine\AutomationTool\Logs\C+Program+Files+Epic+Games+UE_4.21\UBT-LerkersServer-Win64-Development.txt for full exception trace)

Took 0.9310479s to run UnrealBuildTool.exe, ExitCode=5

ERROR: UnrealBuildTool failed. See log for more details. (C:\Users\Yas\AppData\Roaming\Unreal Engine\AutomationTool\Logs\C+Program+Files+Epic+Games+UE_4.21\UBT-LerkersServer-Win64-Development.txt)
(see C:\Users\Yas\AppData\Roaming\Unreal Engine\AutomationTool\Logs\C+Program+Files+Epic+Games+UE_4.21\Log.txt for full exception trace)
AutomationTool exiting with ExitCode=5 (5)

BUILD FAILED