st: unrecognized command: tostring ;r(199)

[- <mc_allister@gmx.de>]

Hello,

I use Stata Version 8 and do not know what I am doing wrong:

The command:

tostring time, generate(time_as_string)

leads to the following mistake:

unrecognized command:  tostring
r(199);

Does anyone know why? Is there any other way to say the same with 
another command?

Thanks a lot.
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/