Substring Start or Length Error

Hi group,

I have a numeric field containing a date in YYYYmmDD format (20061026) 8,0
which I need to convert to mm/DD/YYYY (Character field 10,A) ~ The below
code works fine if I actually have a date in the numeric field, but if the
date is all *Zeros (00000000) I get a "Substring Start or Length Out of
Range" Error.  Is this right, or is there a flaw somewhere?

Char10 = %Subst(%Char(Date8):5:2)  +  '/'  +
              %Subst(%Char(Date8):7:2)  +  '/'  +
              %Subst(%Char(Date8):1:4);

Obviously my solution is to check for all zeros and just clear the character
field instead of putting out '00/00/0000' ~ Just wondering why the error...

Thanks,
//Captain Jerry/