[R] Error from lme4: "Error: (p <- ncol(X)) == ncol(Y) is not TRUE"

[Rory Wilson]

Hello all, I am trying to run a random intercept model using lme4. The random effect is a factor of 29 possibilities, making a model with one random effect (one level). It is just a linear model. There are 713 observations. However, when trying to run the model I receive the error "Error: (p <- ncol(X)) == ncol(Y) is not TRUE",
a search for which reveals somewhat surprisingly little. Has anyone seen this before? Note that if I simply change the random effect into a fixed effect and use lm, the model works perfectly.Thank you!Rory
  
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