Using "medeff" with 2 mediators

[Adnan Habib]

Hi,
I am trying to use the medeff command with 2 mediators. I used the following code

"medeff (regress M1 X C)(regress M2 X C)(regress Y X M1 M2 C), treat(X) mediate(M1 M2) sims(1000) seed(619) vce(cluster permno)"

Here,
M1 = First mediator
M2 = Second mediator
X = Primary independent variable
C = Control variables
Y = Dependent variable
permno = Firm ID (unit of analysis is firms)

But once I run this I get an error message "varlist not allowed"

Can someone help me and point out what went wrong? How can I fix this?