2538 - MQRC_HOST_NOT_AVAILABLE (.Net 6)

Here is my code - Please assist

public Hashtable Properties { get; set; }

Properties.Add(MQC.HOST_NAME_PROPERTY, HostName);

Properties.Add(MQC.CHANNEL_PROPERTY, ChannelName);

Properties.Add(MQC.PORT_PROPERTY, PortNumber);

//Properties.Add(MQC.TRANSPORT_PROPERTY, MQC.TRANSPORT_MQSERIES_XACLIENT); Properties.Add(MQC.TRANSPORT_PROPERTY, MQC.TRANSPORT_MQSERIES_MANAGED);

QueueManager = new MQQueueManager(QueueManagerName,Properties);