SEM - Time-dependent explanatory variable in latent growth model

Hello,

I am using the SEM procedure to build a latent growth model for longitudinal data (repeated variable = cog at times 0, 1, and 2).

I am able to include baseline covariates (eg sex in the example below). I would like to include a time-dependent covariate Y measured at times 0, 1, and 2 and I do not seem to be able to make it work. Any advice ?

sem ///
(cog0 <- Intercept@1 Slope@0 _cons@0) ///
(cog1 <- Intercept@1 Slope@1 _cons@0) ///
(cog2 <- Intercept@1 Slope@2 _cons@0) ///
(Intercept <- sex _cons) (Slope <- sex _cons ) , latent(Intercept Slope) ///
var(e.cog0@var2 e.cog1@var2 e.cog2@var2) cov(e.Intercept*e.Slope ) ///

Thank you

André