web application on tablet

I developed two web applications, which should be used on a pc-mswindows and a tablet.
Everything worked fine until now. I don’t now what happened but suddenly the tablet does not react anymore when one presses the pushbutton or a line in a listbox. So the app became useless for the tablet. My clients are waiting for an answer.

Is this a known error? Is there a version problem?

Sorry, forgot to mention the version I’m using 2014r3.1