The errorbar call should be:
errorbar(x, MODESTAMMEQ.Var5, MODESTAMMEQ.Var4,'.r','MarkerSize',6)
since ‘MODESTAMMEQ.Jan1989’ (that likely threw the error) has to be processed in the regexp and datetime calls to be usable as ‘x’.
However the ‘MODESTA’ table does not exist, so the second plot call does nothing, and substituting:
gives a very strange result (at least to me).