As part of an application (I want the user to be able to use fingers instead of the SIP) I have built a keypad. This is to input a decimal value and a tollerance of between 0 & 50%. On pressing 'Enter' it populates the button and the button value is used elsewhere. If the textbox is cleared with the 'C' button and 'Enter' is pressed; in the IDE debugger pressing 'Enter' does nothing - this is what I want. However when Optimised Compiled, on the Device it gives a 'FormatException' or on the desktop it gives 'Input string was not in a correct format' Where am I going wrong?