Fix error while plotting

[lawinslow]

I get the error Error in plot.window(...) : need finite 'ylim' values when using wtr.plot.temp and wtr.heatmap.layers. The example in the documentation doesn't run for me.

 #Get the path for the package example file included 
  wtr.path <- system.file('extdata', 'Sparkling.wtr', package="rLakeAnalyzer")

  #Load data for example lake, Sparkilng Lake, Wisconsin.
  wtr = load.ts(wtr.path)

  # generate default plot
  wtr.heatmap.layers(wtr)
  #Added for completeness
  wtr.plot.temp(wtr)

[lawinslow]

               _                           
platform       x86_64-w64-mingw32          
arch           x86_64                      
os             mingw32                     
system         x86_64, mingw32             
status                                     
major          3                           
minor          1.0                         
year           2014                        
month          04                          
day            10                          
svn rev        65387                       
language       R                           
version.string R version 3.1.0 (2014-04-10)
nickname       Spring Dance