Send value to Property Definitions

Hello,

I'm using vra 7.0.1

I created property definition named Custom.ISO and made this property as a dropdown.I want to send dropdown values to Image.ISO.Name property.  But i am getting this error ;

The following component requests failed: vSphere_Machine_1. Request failed: Machine VRAVM01: CreateVM : The file [ISO_DATASTORE] {Custom.ISO} does not exist..

Blueprint settings ;

Property definitions settings;

can i send values using this medhod ?