Hi, thanks for the info. There is no limitation. Maybe you have a special PDF which isn't interpretet correctly by PDF24 Creator. Most PDF documents should work, but there are problems with some special PDF.
I would be very pleased if you could send me that PDF which cause problems. Please send the document(s) to support@pdf24.org. Then i can look into the program whether there is an bug or not.
Please also check whether you have the latest version because we fix errors with every new version.
If you have problems with merger of the PDF24 Creator, then you can also switch to our online PDF merger. This one uses an other software and it's sometimes worth to give it a try.