Please read the documentation more thoroughly before assuming a topic. The answer from Keith is correct, you have to add error checking and managing to your code.
Please also note that :
Negative discussions of any banking, brokerage and other financial institutions are not allowed.
Your question was
"So, how can the bid and ask price of this other pair be obtained via MQL4 code?"
I don't see that reading it more thoroughly would interpret it in any other way.
My suggestion isn't totally worthless. If you can't use something other than Symbol, then why is it there in the function?
What is the error number, when you get zero? Are you handling 4066? What is your string? Is in in market watch? What is Symbol()/_Symbol?
Don't be asking for help if you want to be insulting.
please do not disrespect other posters unless you would like to be banned..
Note also that there is very little point when the posts are over 3 years old