Why is this one underperforming so much in the U.S....

The Kung Fu Panda, was a big hit when it came out, the second was a modest success domestically, but this does not even look to break even in the United States (its budget is listed at $130-$140 million) and may not make more than $110 million domestically. This is almost $100 million less than the first not including inflation, and about $50 million less than the second one. What do you think caused audiences to tire of this series so quickly.

Another interesting note will be if the third How to Train Your Dragon will perform as poorly domestically, as the first was a huge hit, but the second made less than the first, one has to wonder if the third film will be like a Kung Fu Panda 3, and really underperform.