Yesterday I sent this tx on Ropsten network. It is a transfer for 999 ethers.

eth.sendTransaction({from:"0x8c60d40a2e848251d139fc2b0b6b770bb3351ffd", to:"0xf9e33261328a1cdc62d3dc6b95880656a1f2a5d9", value: web3.toWei(999, "ether"), gas:4700000, gasPrice: 10000000000}); 0x86329f1a1022c4d7cfe7c66b319c31481d66c83e0554980ec1b3e567d6f79c97 

Transaction 0x86329f1a1022c4d7cfe7c66b319c31481d66c83e0554980ec1b3e567d6f79c97 became lost. First 10 hours was seeing on etherscan https://ropsten.etherscan.io/tx/0x86329f1a1022c4d7cfe7c66b319c31481d66c83e0554980ec1b3e567d6f79c97 as a pending tx, but then it just disappeared and it doesn't exist anymore.

Is there any explanation to such a behaviour? Is no guarantee for a sent tx to be mined?