st: error message r(2000)

["louis boakye-yiadom" <louisby@hotmail.com>]

Dear All,
I get a "no observations" error message -r(2000)- when I execute a do file, 
and I'm having difficulty determining what's going wrong. According to the 
error message, I "have requested some statistical calculation and there are 
no observations on which to perform it. Perhaps you specified if exp or in 
range and inadvertently filtered all the data." I don't understand what is 
meant by "filtered all the data". The line that generates the error message 
is:
regress lnW `varlist' if migst1==0
To check whether there are actually no observations, I gave the following 
command (and had the shown output):
count if migst1==0 & !mi(`varlist')
2720
Any help will be appreciated. Thank you.

Louis


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