Define a date in a XML application in Composer

Question

I want to define the mapping of a date in a XML file to a time attribute in my custom document type. But the checkbox in the Property/Content Mapping Setting for "Property is a date, the format is.." is greyed and I can't define a format. The attribute in the repository I specified is defined as time.

I have a second XML application where it is possible to define dates and its format. What is different from this type/XML application? Any ideas?

I'm using Composer 6.7 SP1

mmayr2 · Accepted Answer

Problem solved! I had to update the dtd to the current (5.3) dtd.