Getting Windows MSMQ Queue Length to work

I cannot seem o get the Windows MSMQ Queue Length sensor to work, message queuing has been installed on the PRTG server and started, the queues I want to monitor are on another server on the local network (no domain). When I added the sensor it correctly picked up the queue names on the server and added them as monitors but they all are stuck with the error "Remote computer is not available". I’ve tried the WMI Tester with a custom query of "Select * From Win32_PerfRawData_MSMQ_MSMQQueue" and it works fine. The other WMI sensors are working fine so I can’t figure out why it’s not working, anyone got any ideas?