We are using this slider ( from basic-slider[dot]com )/

it gives the following error as shown in the console debugger......

"Cannot call method removeClass of Null"

The problem is that the images are not properly synchronized & there is no uniformity in the sequence in which the images are displayed
& some images are not displayed which are displayed in previous slide cycle.......

Also there are times when the slide buttons below do not work ....

Any idea of the solution?