Add a string to file .pot using Poedit

Hi,
I want to add a string to a pot document for language, but it says there’s an error.
I have opened file .pot with a text editor and I have add this code

#:D:\Programe\InstantWP\InstantWP_4.3.1\iwpserver\htdocs\wordpress\wp-content\themes\sydney-child/category-38.php:56
msgid “”
“Read more”
msgstr “”

while in my file I have add this one

<?php _e( ‘Read more’, ‘sydney-child’ ); ?>

Then I have downloaded file .pot and I have opened it with Poedit, I have add the translation “Read more”, but when I update it says: “Source code not available. Translations can’t be uploaded by source code because there is no source code in the path specified in catalog properties” (the message was Italian, so I hope to have well translated in English)

Can anyone help me? Thanks