Observations drop in xtlogit procedure

Dear Madam/Sir,

I ran xtlogit procedure (logit fixed-effect model or conditional logit) and saw the following message that many observations dropped. It will be greatly appreciated if you give me an idea what does it mean.

. xtset gvkey
panel variable: gvkey (unbalanced)

. xtlogit futureres gafscore mascore ln_at financing fo sq_segs roa loss lev mb return big4 indspe auditdelay icw stenure i.fyear,
> fe
note: multiple positive outcomes within groups encountered.
note: 1,045 groups (8,388 obs) dropped because of all positive or
all negative outcomes.

Thank you

Sincerely,
HJ