pictures in slider dont fit

Hi,
I use Originative theme. And there is a slider with pictures in it.
It says that the thumbnail size of the pictures for the slider should be 990x409, but when we put that size pictures in it, it cuts of a large part of the bottom.
Who knows what to do?

Thanks

so, found the answer.... In the theme slider it says that pictures should be 990*409. However, looking in de html-code it says 1000*303. That worked.