The problem is that there are more decimal places, because the MaskInput property requires the exact number of decimal places you want to enter.
So, if you want to get a maximum of ten decimal places, you can write
numEditor.NumericType = NumericType.Decimal
numEditor.MaskInput = "{LOC}n.nnnnnnnnnn"
{LOC} .
,
numEditor.MaskInput = "{LOC}{double:1.10:c}"
, .
MaskInput - Infragistics.
MaskInput