st: Why does Stata return an invalid syntax error in this ado file?

[Aaron Kirkman <ak1795mailserv@gmail.com>]

Dear Statalist,

I'm writing a simple ado file, --statetofips--, to assign fips codes
to observations based on the state name. If I run the following code,
I do not receive an error:

##
clear
input str8 state
Alabama
Alabama
Alabama
Alaska
Alaska
Alaska
Arizona
Arizona
Arizona
Arkansas
end

gen int fips = .
replace fips = 1 if lower(state) == "alabama"
replace fips = 2 if lower(state) == "alaska"
replace fips = 4 if lower(state) == "arizona"
##

However, if I run this code, I receive an "invalid syntax" error:

##
clear
input str8 state
Alabama
Alabama
Alabama
Alaska
Alaska
Alaska
Arizona
Arizona
Arizona
Arkansas
end

discard
statetofips state, generate(fips)
##

These are the contents of --statetofips.ado--, which is located in the
same directory as the above do file:

##
program define statetofips
	syntax varname , Generate(String)
	if "`generate'" != "" {
		quietly gen int `generate' = .
	}
	replace `generate' = 1 if lower(`varlist') == "alabama"
	replace `generate' = 2 if lower(`varlist') == "alaska"
	replace `generate' = 4 if lower(`varlist') == "arizona"
	replace `generate' = 5 if lower(`varlist') == "arkansas"
	replace `generate' = 6 if lower(`varlist') == "california"

end
##

I reduced --statetofips.ado-- to its simplest form, and the error persists:

##
program define statetofips
	syntax varname , Generate(String)
end
##


What is causing the syntax error in the ado file?

Thank you,

Aaron Kirkman
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