Paypal, Why?

I was feeling giddy when I went online last Saturday night. First thing I did was check my Yahoo mails and just checked if I got the mail I was expecting. Yes, it's there just right on time. :) I didn't even opened and read the email, I just hurriedly logged on to my Paypal account, went straight to the Withdraw page to withdraw my money. (Yes, it's my salary I was excited about! HAHA) But to my surprise, it said "Funds withdrawn must not exceed your available balance." I tried again wondering what might have I done wrong but still I can't transfer funds saying I have $00.00 balance. Whaat?! O.o Can you say that again?! :[ (I'm doomed!!)

I didn't know what's wrong so I went to the main page to check my actual balance. I was really excited to withdraw my money hence missing the note in My Account page which says I have a pending balance. Pending balance? What do you mean by that? I checked my Yahoo mail again and read the email I got from Paypal, and yes it says that my client's payment is under review. But why? T.T How long do I have to wait!?? Did anyone had this problem before?

I've talked with my client and he said maybe this happened because he sent the money using his mobile (with a new number) while he's on a train in China. (he's in a business trip) And maybe Paypal has seen this transfer suspicious since he's in a different country. Does this makes sense? I looked through Paypal, and they stated that it'll be under review for 24 hours. But I've read in the Internet that it'll take 21 days. How true?? Do I really have to wait that long?! :[