R help - Nov 2011 - Error in gls function in loop structure

Hi, r-users

I got a problem when I try to call a *gls* function in loop structure.
The gls function seems not able to recognize the parameters that I pass
into the loop function!
(But, if I use lm function, it works.)

The code looks like this:
================================================gls.lm <- function(Data, iv1,
dv1)
{
gls.model <- gls(Data[ , dv1] ~ Data[ , iv1], correlation = corARMA(p=1),
method='ML',na.action=na.omit, data = Data)
print(summary(gls.model))
}

regResultMatrix <- gls.lm(DR, 'Period', 'Aircraft')
regResultMatrix <- gls.lm(DR, 'Period', 'Total.Employees')
=================================================The "DR" is the data
in excel file which includes three columns: Period,
Aircraft and Total.Employees.
And, I got the error message like this:

*Error in eval(expr, envir, enclos) : object 'dv1' not found*

Could any one tell me what is going on there?

Thanks in advance.
Miles
-- 
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Miles Yang
Mobile：+61-411-985-538
E-mail：miles2yang@gmail.com
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