Create a valid PDF/A

I'm in trouble using PDF Creator 1.6.0 in order to create a PDF/A.

The pdf is created, open it with Adobe Reader show me that it's PDF/A.

Checking it's PDF/A integrity with

reports me the following errors:

Validating file "OL030_12.pdf" for conformance level pdfa-1b
Wrong namespace '(null)' for value type 'ResourceEvent'. The required namespace is ''.
The value of the key N is 4 but must be 3.
The document does not conform to the requested standard.
The document doesn't conform to the PDF reference (missing required entries, wrong value types, etc.).
The document's meta data is either missing or inconsistent or corrupt.



can anyone provide me suggestions?

Many Thahks