Hi everyone,
I'm very new to Stata and I am very confused my this error. I have created two variables to describe flights from differents airports in Miami to different airports in Dallas. Then, I mean to find a correlation between the prices of plane tickets to the same city, but different airports. The sum function works and I believe I have no missing values, so I have no idea what may be causing the error. I will paste in my code for reference

pwcorr MiamitoDallasPrice1 MiamitoDallasPrice2
no observations
r(2000);