Although an inputfield should work with any value (in QlikView there are only two types of values: numerics and literals) I do not recommend using it for several reasons, being performance the first of them.
By the way, what do you mean is not working?
Is it not allowing to add the value you want to?
Are you using it in a table box or a listbox or in a chart?
Have you specified in the script that the field is going to be used as INPUTFIELD?
Does it work in QlikView Desktop but it doesn't in Ajax?