Multiple-membership models with lme4

Hi everyone,
I am working on estimating multiple membership models with lme4, following
the instructions posted here
https://bbolker.github.io/mixedmodels-misc/notes/multimember.html

Below is my code, in which J2 is the number of clusters (in my case, the
clusters are clique-2s, and J2=1345) and N is the number of participants
(N=968). These participants belong to 0 to 11 of the clique-2s.

I got the below error. Could anyone help? Thanks!

fake2 <- rep(1:J2, length.out=N)
lmod  <- lFormula(formula=y~1+(1|fake2), data=data)

Error: number of levels of each grouping factor must be < number of
observations



Best,
Sijia