When you specify %SUBJECT%, select "variable" for the type and not "literal".
Thank you Jasmin,
the matter is that in "Email start point properties" --> Inputs/Outputs --> Input Data filter, the input variables do not have the dropdown list for the type (literal, variable, xpath,....)
I.'m using Livecycle ES2 9.0
How can I do?
This is a bug which is being addressed in Service Pack1.
As Jasmin said you can work around this issue by changing literal to variable.
However, for now you need to do this in the adminui not Workbench.
Go to: Services->Applications and Services->Service Management.
Find your application, select it and you should see the Endpoints panel.
Select the Email Endpoint.
Down at the bottom under Input Parameter Mappings change the dropdown to Variable from Literal and save the endpoint.