title: Error in X %*% fixef(object) : non-conformable arguments
body: <p>I get this error when I try to predict the nlme. And I don't know how to solve it my code is the following: </p>
  
  <pre><code>mod1.lme &lt;- lme(pRNFL~ status +  Time:status, random= ~1|DBID/Eye_ID, data = long, na.action = na.omit)
  summary(mod1.lme)
  
  
  plot(fitted(mod1.lme), resid(mod1.lme), col = long$status) 
  dim(long)
  length(fitted(long))
  length(fitted(mod1.lme))
  
  long2 &lt;- long[!is.na(long$pRNFL),]  
  dim(long2)
  plot(long2$pRNFL, fitted(mod1.lme))
  plot(long2$pRNFL, fitted(mod1.lme), pch = 16, cex = 0.8, xlab = "Measured pRNFL", ylab = "Model fitted pRNFL")
  abline(a = 0, b = 1, col = "red", lty = 2)
  
  A_AQP4 &lt;- subset(long, status=='A-AQP4')
  F_AQP4 &lt;- subset(long, status=='F-AQP4')
  N_AQP4 &lt;- subset(long, status=='N-AQP4')
  A_MOG &lt;- subset(long, status=='A-MOG')
  F_MOG &lt;- subset(long, status=='F-MOG')
  N_MOG &lt;- subset(long, status=='N-MOG')
  
  
  x &lt;- c(0:800)/100
  A_AQP4data &lt;- data.frame(Time = x, status = "A-AQP4")
  F_AQP4data &lt;- data.frame(Time = x, status = "F-AQP4")
  N_AQP4data &lt;- data.frame(Time = x, status = "N-AQP4")
  A_MOGdata &lt;- data.frame(Time = x, status = "A-MOG")
  F_MOGdata &lt;- data.frame(Time = x, status = "F-MOG")
  N_MOGdata &lt;- data.frame(Time = x, status = "N-MOG")
  
  yA_AQP4 &lt;- predict(mod1.lme, newdata = A_AQP4data, level = 0)
  yF_AQP4 &lt;- predict(mod1.lme, newdata = F_AQP4data, level = 0)
  yN_AQP4 &lt;- predict(mod1.lme, newdata = N_AQP4data, level = 0)
  yA_MOG &lt;- predict(mod1.lme, newdata = A_MOGdata, level = 0)
  yF_MOG &lt;- predict(mod1.lme, newdata = F_MOGdata, level = 0)
  yN_MOG &lt;- predict(mod1.lme, newdata = N_MOGdata, level = 0)
  </code></pre>
  
  <p>Any idea of how can I solve it please? The error is the following: </p>
  
  <pre><code>&gt; yA_AQP4 &lt;- predict(mod1.lme, newdata = A_AQP4data, level = 0)
  Error in X %*% fixef(object) : non-conformable arguments
  </code></pre>
  
  <p>This is a summary of mod1.lme (called here mod2) in case this is useful 
  <a href="https://i.stack.imgur.com/M4BjB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/M4BjB.png" alt="enter image description here"></a>
  [<img src="https://i.stack.imgur.com/X1KcR.png" alt="enter image description here">][2
  <a href="https://i.stack.imgur.com/KH2u2.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KH2u2.png" alt="]"></a></p>
  
  <p>The levels of my variables are different
  <a href="https://i.stack.imgur.com/8alTO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8alTO.png" alt="enter image description here"></a></p>
  
  <p>What am I doing wrong? </p>
  
  <p>Thank you!! </p>