I had seen so many questions about joining multiline log as in OMW the Log Interceptor is parsing line by line, so if your data is scattered on different lines it can not be monitoring unless you imply a pre-processing script.
I have created the below script is to join multiple lines together but if match a certain keyword
Save the contents to joinlines.vbs
It can be implemented in different ways:
You can create a log file policy to search for your error message in each line as the sample below
1- You may create your rule to search for the word error and to send message and we can use the script as automatic action to get the previous lines and to append it to the annotation
2-You can create the policy to pre-process the log and write the output to a text file to be read.
cscript /nologo log.vbs backup.log ERROR >c:\windows\temp\joinedlines.txt