New-PAMRequest: Cannot validate argument on parameter 'Role'. The argument is null or empty

Hello, I am trying to configure PAW scenario from this link: https://docs.microsoft.com/pl-pl/microsoft-identity-manager/pam/step-7-elevate-user-access

I stuck on the moment, when I have to run following powershell commands:

Import-module MIMPAM
$r = Get-PAMRoleForRequest | ? { $_.DisplayName –eq "CorpAdmins" }
New-PAMRequest –role $r
klist purge

I have following error:

PS C:\Users\Administrator.priv> $pr = New-PAMRole -DisplayName "CorpAdmins" -Privileges $pg -Candidates $sj
New-PAMRole : Role 'CorpAdmins' already exists in MIM.
At line:1 char:7
+ $pr = New-PAMRole -DisplayName "CorpAdmins" -Privileges $pg -Candidates $sj
+       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [New-PAMRole], InvalidOperationException
    + FullyQualifiedErrorId : GeneralServerError,Microsoft.IdentityManagement.AdminPamCmdlets.NewPAMRoleCommand

I have following role in my system, which I've validated running following command:

PS C:\Users\Administrator.priv> $pr = New-PAMRole -DisplayName "CorpAdmins" -Privileges $pg -Candidates $sj
New-PAMRole : Role 'CorpAdmins' already exists in MIM.
At line:1 char:7
+ $pr = New-PAMRole -DisplayName "CorpAdmins" -Privileges $pg -Candidates $sj
+       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [New-PAMRole], InvalidOperationException
    + FullyQualifiedErrorId : GeneralServerError,Microsoft.IdentityManagement.AdminPamCmdlets.NewPAMRoleCommand

What can be the reason of such situation?