True, Brussels on LH tour was very poor. They even started to sell the cheapest tix officially for a ridiculous low price in the weeks before concert.
Nevertheless, the attendence was 30.000 people, but that stadium has capacity for 50.000.

Some reasons for these low sales figures were:

Price for golden circle was 100 euro (compared to 64 euro in holland the day before)
Even the 2nd price was ridiculously high.
Poor marketing promo for the concert.
During 95 and 2009, Bon Jovi always draws a crowd about 30.000 people (except for once in 2000 when 50.000 people came to see them in ostend for the crush tour).


Best place for them to play in Belgium is in Werchter. This festivalground can hold to 80.000 people, but since it ain't a stadium it doesn't matter if only 30.000 people attend the show. (in stadiums suddenly half of the seat remains empty)


By the way, Amsterdam 2009 was far from sold out either, but they covered the empty seats with some sort of black drapes.