problem with executing the Invoke-LyncSpray command

[mardmz]

>> Invoke-LyncSpray -userlist users.txt -password Welcome1 -AutoDiscoverURL https://lync.example.com/Dialin -verbose [*] Retrieving S4B AutoDiscover Information Unable to retrieve or process AutoDiscover URL: System.ArgumentException - Invalid JSON primitive: . At C:\LyncSniper-master\LyncSniper.ps1:168 char:7

• throw "Unable to retrieve or process AutoDiscover URL: " + $_.E ...

• 
  + CategoryInfo          : OperationStopped: (Unable to retri...ON primitive: .:String) [], RuntimeException
  + FullyQualifiedErrorId : Unable to retrieve or process AutoDiscover URL: System.ArgumentException - Invalid JSON
  primitive: .