Dear all Statalist experts, today I read the new function of Difference-in-Difference test from STATA17 called xtdidregress

I applied this code to my data and got the results below:
Code:
xtdidregress (FAT_w1  $tatcov_) (post33treat1), group(TYPE2) time(year1)
Among them, FAT_w1 is the dependent variable, $tatcov_ is the covariates, post33treat1 is a binary variable( receiving value of 1 for the treatment group after event day and 0 other wise), TYPE2 is the firm type and year1 is the real year in me data sample. Array




After that, following the guide of the same link above, I conduct a parallel trend test visually by using the syntax
Code:
estat trendplots
However, the results turns out an error like that Array


I am wondering why they said "treatment assignment times vary" here. Because in my datasample, I only have one event date and examining 3 years before and 3 years after this event date.



Could you please kindly to help me in sorting it out?

Many thanks and warmest regards.