When this operation is not working? It's when reading the second line, the third, ??? Try adding a Debug Sampler to see what exactly it is reading and what it's not.
Verify if it is a blank line somewhere in your file because "If a blank line is detected, this is treated as end of file ..." (extracted from JMeter functions page) Verify if it has reached the end of the file. Can you share your JMX and CSV files? If not, could you detail what components you are using? I was thinking that reading the second column and doing the next operation, before reading the first column, will interfere in reading the first column on the next row, but I tested it and worked fine. Hope it helps you.
