How to query custom attribute

Hi,

I'm trying to create an alert rule with the use  of custom attribute from the Host (node) so I can send the alert to the responsible party via the Email To: field stored in a custom attribute field called 'PrimaryContact'

I can query standard attribute of the host but not the custom attribute of the host:

Part of the code in the alert body:

---

No heartbeats are being received for:

VM = ${N=SwisEntity;M=Name}

Host = ${N=SwisEntity;M=Host.HostName}

Cluster = ${N=SwisEntity;M=Host.Cluster.Name}

DataCenter =${N=SwisEntity;M=Host.Cluster.DataCenter.Name}

vCenter = ${N=SwisEntity;M=Host.Cluster.DataCenter.VCenter.Name}

${SQL:Select IPAddress From VIM_Hosts where NodeID=${N=SwisEntity;M=Host.NodeID}}   <---- works

${SQL:Select PrimaryContact From VIM_Hosts where NodeID=${N=SwisEntity;M=Host.NodeID}}   <---- Not working

Can anyone help? Thanks.