Dattobd fails to install

UrBackup is running beautifully but there are errors in the log relating to dattobd.
When I reinstalled it I realised that it fails to install properly. Here is a screenshot:

It states that the kernel headers are not installed but when I check /usr/src/kernels, they are there with the correct version.
Can anyone explain what I’m doing wrong?
I am backing up my FreePBX phone system, which is installed on Centos 7.