Transponder Codes Starting with Zero

Hi All,My apologies if this is covered elsewhere - I DID do a search first....Anyhow, I've just had an ..er embarassing experience on VATSIM where I was unable to enter my assigned sqk of 0710.Whenever I attempted to decrement the first digit below a value of '1', the transponder's display decreased to three digits! The same happens if you attempt to increment beyond "7".Have I found a bug & do I win a t-shirt? :-wink2