tap and hold for insert white frame

The interface for iStopMotion for iPad says that one just has to “tap and hold” to insert a white frame. I have tried this to no avail. No matter how long I hold, it still takes a regular frame. VERY frustrating. What am I doing wrong? Or is this a bug?

Maybe the description is somewhat misleading. You just have to hold the capture button for about a second or so and a popup menu will appear where you can select either a white image or a black one. Does this work for you?