I have data with two factors TREATMENT and TIME both with two levels and a dependent variable RATIO. Besides random intercept for subjects, I want to specify random slopes for both of the independent variables for the mixed effect model in R using lmer.

Currently I have the following model

lmer(RATIO ~ TREATMENT + TIME + (1 + TREATMENT + TIME | SUBJECT), data=my.data)

I have the following questions.

1. Is it theoretically correct for specifying different random slopes for treatment and time?
2. What could be the reason that the model does not converge? I.e. it gives the following warning

Thanks in advance