[R] lme: object is not a matrix

[zelfortin]

Hi, 

make sure your data is in a data frame:

Data <- data.frame(t,can2p,code)

just specify in which object you find those specific variables by using 
object$ before each one.

I hope this solve the problem. If not, post your script, it's really hard 
to work with only an error message!

Cheers

JM