Hi coranto, and welcome!
Without seeing a sample of your report, I would recommend using the "End of Left Justification" setting in the "End Field On" option group.
If you're still not getting what you need, and you're able to post a sample of the report (you can always "xxx" out confidential data), please click the CODE button just below message entry box, and place the sample between the CODE tags. This really helps.
Can I define a field to be a certain width and just have it grab all rows until it hits the next record (which is successfully defined in the detail template)? /b[/quote]Kruncher has really answered this one as well as possible given what I can visualise from your description of the problem. The 'None of the above' option should do what you want it to do, I would think, unless there is some other reason that intervenes.
A couple of simple things that are easy to overlook just in case this falls into that category.
Does your field definition have enough characters width defined for both data and display to accomodate the longest descriptions?
Do the fields overlap page breaks (defined by template OR set as defaults in the Monarch parameters)? If so are there any possible aspects of the 'gaps' that might cause the process to think it has found the occurrence of another template when it has not? (A long shot but not to be overlooked if no other explanation seems to apply.)
When you define the template it should be possible to see what will be included in the selection on the screen. If that looks OK for the records that you are not getting correct results for then I would suspect the first check above may be most likely.
But if the selection looks like it will not work then perhaps some other constraint is getting in the way. It is just possible that running the verify routine might expose something though I don't think it is generally used for checking variable fields.
If none of the suggestions so far work for you then I think we would need to see a sample of the layout - a problem record preferably - to be able to come up with a more helpful suggestion.