Why was the Lionel Brogden v. state case appealed?

I assume that you are asking about the case of Lionel
Brogden v. State of Maryland.  This was a case from
2004.

If this is the case you are asking about, the case
was appealed because of a set of supplemental instructions given by the judge to the
jury in response to questions that the jury had.

The
defense argued that the judge's instructions to the jury were improper.  This was
because the judge brought up a possible defense to the charge against the defendant. 
The defense appealed on the grounds that this defense had nothing to do with the case
and had never been put forward by the defense itself.

So,
the point at issue here was whether the judge made a reversible error by bringing up
this defense when the defendant and his lawyers had not put that particular defense
forward themselves.