Created Unassigned: get-scsmobjecttemplate: value cannot be null [11507]

i use the smlets to automate tasks in orchestrator.
I have the smlets installed and succesfully working for a few weeks.

no suddenly when i do the following:
get-scsmobjecttemplate -displayname "templatename"

i receive the error:
Get-SCSMObjectTemplate : Value cannot be null.
Parameter name: input
At line:7 char:18
+ $FoundTemplate = Get-SCSMObjectTemplate -DisplayName “templatename“
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Get-SCSMObjectTemplate], ArgumentNullException
+ FullyQualifiedErrorId : System.ArgumentNullException,SMLets.GetSCSMObjectTemplateCommand

the Get-SCSMObjectTemplate command without parameters returns the complete template list correctly without errors.

any ideas?