Use command gen id = _n to generate the variable id used in spreg ml $ylist $xlist ,id(id) dlmat(weight1) nolog

Use command gen id = _n to generate the variable id used in spreg ml $ylist $xlist ,id(id) dlmat(weight1) nolog

Source: https://www.stata.com/statalist/archive/2005-04/msg00946.html