hi, guys! I'm wondering a question that when I use grreq to plot the coefficient of quantile regression, strictly live up to the example it gives, but doesn't work.
The code in the example is：

. webuse auto, clear
. xi: qreg price mpg i.foreign*i.rep78 headroom
. grqreg, cons ci ols olsci

and the it hints:
o._IforXrep_1_2 invalid name

which means I can't add the dummy varibale in it, because when i delete the dummy, there is no problem, but once they are added, then it doesn't work

How can I solve this problem? I'm quite upset
Thanks soooo much!