I turn off the enforce unique values and do the same as you told, "nf-hidden" doesn't seem to work, other than that it works perfectly!!!
I have also created my own error message
Can you tell me how can I make the "nf-hidden" works? Just type in "nf-hidden", or I need to select this function from the inline functions?
I'm not technical, Zoe, you'll be much better off with the advice you get from gurus like Paul and Cassy. But I'll see if anyone here in the office can pop by with a reply.
Thank you for marking a correct answer above, it's hugely helpful for other people who use search for questions about similar issues!
Thanks Frank! To be honest, so far, keep asking questions and mark the correct answer are the only two things I can do here..., without you guys here to helping people like me who has 0 background in IT and know only very little about coding, I believe I have already gave up on this.
I appropriate everyone who come to help me or even just come to read my question and tell me that they are facing the same issue, either way encourage me to forward bit by bit and learn more.