[R] Very confused with class

[Richard M. Heiberger]

Dan,

The real problem is the use of csv files.  csv files don't handle missing
values
("#VALUE" is most likely from Excel), dates, or other complications very
well.

Read your Excel file directly into
R with one of the packages designed specifically for that purpose.  I
recommend
RExcel (Windows only) which allows complete two-way communication between R
and Excel.
Missing values and dates are handled correctly.
You can download the RExcelInstaller package from CRAN.

Rich