Ethereum Wallet does not support Bitcoin or Bitcoin wallets. Therefore there is no way to actually send and/or store Bitcoin to your Ethereum Wallet.
What you can do is send Bitcoin through a service like Shapeshift which will receive the Bitcoin and send the equivalent amount of ETH to the address you provided. Then you will have ETH, not BTC.
It is impossible to answer your question without knowing what service you used to turn your BTC into ETH. If it is ShapeShift, you need to contact their support. If it is another exchange, such as Kraken or Poloniex, you need to contact their support.
If you are indeed synced and the balance of your address also shows 0 on etherscan.io, then the service you used to turn BTC into ETH probably had a hiccup or something went wrong or something got delayed. Reach out to them and determine what happened.
If you want quick and easy help then be helpful! Provide all information up front. The random support person is not magic and does not know what you did unless you tell them! Provide exactly what you did, where you did it, how you did it, when you did it, the address you sent BTC from, the amount of BTC you sent, and the ETH address you provided.