$20 gone from my account?

Hi,

I'm new to fiverr and earned $44 in the first 3 weeks. I transfered $4 to my account (because it's all that was available...why....i would love to know too) , but after my transfer it stated that my balance is now $40, which is normal right, but then 2 days later it shows that i have earned $20 so far this month. What happened to the other $20? This upsets me and the fact that i have $4 available at the moment to paypal. Why not the full amount if i wanted to? ?????

Please help me out here. Thanks