[R] error message when using strptime

[Kara Przeczek]

I am new to R and have been struggling with the following problem. I apologize if there is an obvious answer that I have missed.
 
I bring in a .txt file (pyr_h.txt) that has a DateTime column in the format "yyyy-mm-dd HH:MM"
When it comes into R, R does not recognize it as a date/time format.  
 
     Date        Time      DateTime              N_Wm2  S_Wm2
1   4/1/2008   01:00    2008-04-01 01:00    0.0000    0.00000
2   4/1/2008   02:00    2008-04-01 02:00    0.0000    0.00000
3   4/1/2008   03:00    2008-04-01 03:00    0.0000    0.00000
4   4/1/2008   04:00    2008-04-01 04:00    0.0000    0.00000
5   4/1/2008   05:00    2008-04-01 05:00    0.0000    0.00000
6   4/1/2008   06:00    2008-04-01 06:00    3.1655    2.56175

 
CODE:
pyr_h = read.table("H:/MastersInfo/data/Figures/Tables/pyr_h.txt",header = T, sep = "\t")
 #  convert Date to date format
pyr_h$Date = as.Date(pyr_h$Date, format = "%m/%d/%Y")
 #  convert DateTime to number format
pyr_h$DateTime = strptime(pyr_h$DateTime, format="%Y-%m-%d %H:%M")
 
This strptime command works on another .txt file of mine with the exact same date/time stamps, but when I try it for this file, it gives the error message:
 
Error in `$<-.data.frame`(`*tmp*`, "DateTime", value = list(sec = c(0,  : 
  replacement has 9 rows, data has 1570

I tried creating a vector: 
 
tmp <-strptime(pyr_h$DateTime, format="%m/%d/%Y %H:%M")
 
When I queried the length of this vector, it was 9, yet when I print the vector there are 1570 objects. 
Any idea what is going on here? I have tried formatting the DateTime different ways in Excel, recreating the .txt file, changing the strptime format, and rebooting R yet nothing seems to be working.
Thanks SO much!
Kara
 
Kara Przeczek
M.Sc. Candidate  NRES - Environmental Science
University of Northern B.C.
3333 University Way
Prince George B.C   V2N 4Z9
Phone: (250) 960-5427
przeczek at unbc.ca