testing IIA with mlogtest, hausman - error message: no coefficients in common

[Anna Novaresio]

Dear all,
I am running a multinomial logistic and I want to test the IIA with the Hausman test, but when I run this code

mlogit class_EMPL_EQUIP l(2)(log_GREEN_ICE_ADJ log_HYBRID_ADJ log_ELECTRIC_ADJ  ... )  i.YEAR, base (3)
mlogtest, haus

I get this error

Hausman tests of IIA assumption (N=258)
Ho: Odds(Outcome-J vs Outcome-K) are independent of other alternatives
no coefficients in common; specify equations(matchlist)
for problems with different equation names.
r(498);

Anyone could tell me what is not working out, please?
PS When I run the Small-Hsiao test I get no error and no violation of the IIA.