DKIM signature valid or not valid?

Im using Custombuild 2.0
I followed this article to install DKIM: https://help.directadmin.com/item.php?id=569
Version Exim 4.89_1
Exim conf Version 4.5.7

I now did several testing, and seems that it has nothing to do with the PDF file. Even when I send mails without PDF have same error.
And I have exactly the same when I send the email from Squirrelmail. But only when I use the following body:

In bijlage de transportopdracht voor 04/12/2017, BE-20 Antwerpen Katoeatie - Luithagen – BE-23 Westmalle CIB Magazijn Westmalle.

---------------------------------------------------------------------------------------------------
Naam bedrijf
straat, postcode city, België
Tel.: telefoor | Fax: faxnummer

[email protected] | https://www.xxx.com

All our transactions are subject to the Belgian Freight Forwarders Standard Trading conditions 2005.
The text of those conditions has been published under number 0090237 in the Aexe au Moniteur Belge dated June 24th, 2005, and is also available on our website.

(I removed some private data)

Then I have following error in hotmail:

Authentication-Results: spf=pass (sender IP is xx.xx.xx.xx)
smtp.mailfrom=xxx.com; hotmail.com; dkim=fail (body hash did not verify)
header.d=xxx.com;hotmail.com; dmarc=pass action=none
header.from=xxx.com;

When I send the mail with another body I have DKIM pass. (also on dkimvalidator.com)
There I have following error:

Public Key DNS Lookup

Building DNS Query for mailsrv._domainkey.xxx.com
Retrieved this publickey from DNS: v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAxjIlKDuaHvM2yvjUTXDKZLNpPQKOEsOiaHcUPS/6UTm5dU5PQ8T7eC7Y9HLOrLL/PQKlH3xqw9K/hHJF4Xrdyx4B6Btc8l3gZFyhgUW07YOKuHDt113hvUZBkjg/S4TKWfJkSzvK7MXgWxoJA+5uNcSUhzaKk7jVn4ahperQXSdCYPMf/EYGzaDDjUYQ/FrSFgJWc57xE7mN10Fd7KErNI5zCg+xX1yULrE/Tz1VoYtulEWPbBSA7fQnYvV2lJ0zfP1cEHbSWlR7EpZ6qe9yW1de5oQDb4GMCtyyzgNoCeGN7DgJQtyIEyotS7RtKZ5n62wXDuDa7JqhoBWjCU2iqwIDAQAB
Validating Signature

result = fail
Details: message has been altered

So what is wrong and how is this possible?
It seems that only DKIM is failed when I use a specific body message.

When I send same mail from my Google account I have DKIM pass. So it's only Exim is affected. Maybe a bug?