Powershell Change a Virtual Server Default Pool

the command I am using is "$ActiveLB.LocalLBVirtualServer.set_default_pool_name('/Common/Test-Pool', '/Common/FL-External-Sitedow')". I gett the following error message Exception calling "set_default_pool_name" with "2" argument(s): "Exception caught in LocalLB::urn:iControl:LocalLB/VirtualServer::set_default_pool_name() Exception: Common::OperationFailed primary_error_code : 16908342 (0x01020036) secondary_error_code : 0 error_string : 01020036:3: The requested pool (/Common/FL-External-Sitedow) was not found." At C:\Users\ddeer\Downloads\Powershell_ActiveUnit-Test.ps1:28 char:2 + $ActiveLB.LocalLBVirtualServer.set_default_pool_name('/Common/Tes ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : NotSpecified: (:) [], MethodInvocationException + FullyQualifiedErrorId : SoapHeaderException