Pass email's subject property to process variable, maybe not formatted well

Hi everybody.

I have a process model that starts after a trigger from an email received.

When i save the subject of the mail, witht the mail's property "Subject", I pass the subject as a rule input for a expression rule.

Unfortunally, the rule doesen't work well, but if I pass the subject of the mail as a wired string, the expression rule works correctly.

I DON'T KNOW WHY.

I suppose it's something about the format of the subject passed from the mail, but I tried with functions like "touniformstring" but nothing.