Sorry! I just realized that I accidentally gave an invalid i value to the function. All good now!

Besides answering the question, the output picture seems to be not working. It would be appreciated if someone can let me know how I can properly show the output. 

@Ronan Then how could I reconstruct the vectors A and C? The vectors A and C cannot be constructed while using A[i], C[i] syntax.

Thank you for answering this, @acer.

However, I found this sneaky behaviour very confusing. I checked the online help before and the fact that Gcd is changed after loading the package is not mentioned in the package help and the Gcd function. 

I hope things like this can be better documented than this... I spent hours trying to debug this...