Q:

Asking a new question for a complement of an old question? 

Basically, I implement a solution of this question:
Spring: Convert String from View to a Calendar Object
But I'm getting an error. 
Should I answer this question with my error asking how to solve or create a new question with a link to this question? 

A:

Ask a new and complete question.  Don't just state your error and then link to the other question.  Reference it, certainly, but include the relevant code in your question as well.  It needs to be self-contained.  
In this regard both "How to Ask" and "How to create a Minimal, Complete, and Verifiable example" in the Help Center are good reads.  
Don't post it as an answer because ... it's not an answer. 