Devops Nuget versioning byBuildNumber does not work

I want the version numbers of the Nuget package to be incremented and human readable with every version pushed to the Artifacts store. This is my yaml.

variables:  feedName :  'MyNugets'  buildConfiguration: 'release'  name:  $(Year:yyyy).$(Month).$(DayOfMonth).$(Rev:.r)pool:  vmImage: windows-lateststeps:- task: DotNetCoreCLI@2  displayName: 'Build'  inputs:    command: 'build'    projects: '**/*.csproj'    arguments: '--configuration $(buildConfiguration)'- task: DotNetCoreCLI@2  displayName: 'Pack'  inputs:   command: pack   versioningScheme: byBuildNumber- task: NuGetAuthenticate@1  displayName: 'NuGet Authenticate'- task: NuGetCommand@2  displayName: 'NuGet push'  inputs:    command: push    publishVstsFeed: '$(feedName)'    allowPackageConflicts: true

Whatever suggestion I could find on SO or other google result. None of them seems to be working. I always get this error.

##[error]Could not find version number data in the following environment variable: BUILD_BUILDNUMBER. The value of the variable should contain a substring with the following formats: X.Y.Z or X.Y.Z.A where A, X, Y, and Z are positive integers.

Any suggestions ?