Error in Xderiv %*% fixef(lmeObject)[derivForm$indFixed] : non-conformable arguments

[yugangjia]

Hi, @drizopoulos,
I am trying to use derivForm with splines and getting the following error:
"Error in Xderiv %*% fixef(lmeObject)[derivForm$indFixed] :
non-conformable arguments"

Can anyone show an example how to set the derivForm when you use splines in the linear mixed effect model?
Here is my code

fitLME_poly <- lme(sofa_recent ~ ns(hr_day, 3)*ethnicity+U_sofa_adm+age10+male,
random = list(stay_id = pdDiag(form = ~ ns(hr_day, 3))), data = mdat)
fitCox_poly <- coxph(Surv(icu_day,died) ~ ethnicity+age10+male+U_sofa_adm,data=mdat.id,x=TRUE)

dForm <- list(fixed = ~ dns(hr_day, 3) + dns(hr_day, 3)*ethnicity, indFixed = c(2,3,4,11,12,13,14,15,16,17,18,19),
random = ~ dns(hr_day, 3) , indRandom = c(2,3,4))

fitJM_pwph_poly <- jointModel(fitLME_poly,fitCox_poly,timeVar="hr_day",
method="piecewise-PH-aGH",
parameterization = "both", derivForm = dForm,
control=list(verbose=TRUE,iter.EM=100))
Thanks

[drizopoulos]

There are example in my course notes, and sample script files in my website.