Icing Sheet is Too Moist or doesn't want to come of from the backing Sheet
One of the ingredients is Corn Flour, if the image is out for too long in moist conditions the corn flour will soak up the air and stick to the backing sheet.
Humidity in the air and dark colours in printing is the most common causes for a moist sheet. Remedy: Preheat your oven to +/- 70 degrees Celsius. Place the image facing upwards in the oven for 2 to 3 minutes. remove from the oven and place on a dry clean surface. (a granite surface works well.) Leave 1 to 2 minutes to cool. Peel of gently from the back sheet if the sheet feels steady enough. Pat image gently to prevent air bubbles forming in the cake. Process might need to be repeated if the sheet is still a bit soft and don't release easily.