Building an interfaces Alert with Nodes Custom Properties

Hi.

i tried to build an interfaces alert, and include some nodes custom properties. but in the sent e-mail, i only get the variables instead of the text those should invoke.

¿Is there any way to do this?.

This is an example.

CLIENTE: ${N=SwisEntity;M=CustomProperties.CLIENTE}
 SUCURSAL: ${N=SwisEntity;M=CustomProperties.SUCURSAL}
 CIUDAD: ${N=SwisEntity;M=CustomProperties.City}

 RESPONSABLE: ${N=SwisEntity;M=CustomProperties.AREA}

This works allright with node based alerts, but with others not,  and this info is fairly important, we are concentrating all alerting in our service desk since they operate 24x7, and this info should lessen the time and escalation errors

Thanks in advance