PDF download damaged

Hello just a question,
I have a download server action following this approach

However the downloaded pdf displays a message that it is damaged.

Although if I use a static value to download the same file, opens successfuly.

Any ideas?
Thank you!

PS To make it more clear, the files that need to be downloaded works ok. The issue is that the downloaded file cant be opened and Acrobat displays the message that it is damaged