[R-es] error con grid.arrange

Muy buenas, trato de poner 5 ggplots juntos con  grid.arrange y me da este
error:

grid.arrange(pdpPL, pdpPs, pdpCl, pdpUr, pdpHP, nrow = 1)

Error in `$<-.data.frame`(`*tmp*`, "wrapvp", value = list(x = 0.5, y = 0.5,
 :
  replacement has 17 rows, data has 30


Algunas pistas (todo igual para los 5 PDPs):

class(pdpPL)

[1] "data.frame" "partial"

head(pdpPL)

PrimLand       yhat
1     0.00 0.12917927
2     0.02 0.17702830
3     0.04 0.13464397
4     0.06 0.15734838
5     0.08 0.11623142
6     0.10 0.05936711

str(pdpPL)

Classes ?partial? and 'data.frame': 51 obs. of  2 variables:
 $ PrimLand: num  0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 ...
 $ yhat    : num  0.129 0.177 0.135 0.157 0.116 ...

Gracias,
Manuel