RT Doesn't send correct message body

I have migrated my RT instance from 3.8.7 to 4.0.19.
The main problem is that when I click into a ticket then click into Actions -> Respond, then
I write a answer, the receiver doesn’t receives the message body that I’ve just typed.
It receives “{$Transaction->Content()}” instead of the message that I’ve typed.
How solve it?

Issue solved…

On migration, old templates are displayed into RT interface as “perl type” but seems that are processed as “text type”.

Just entered on each template then click save button then automatically type has changed to “perl”.