Solved!
In Block n. 183000 there aren't transactions:
eth.getBlock(183000)
{
difficulty: 2,
extraData: "0xd783010600846765746887676f312e372e33856c696e75780000000000000000a2111cb9859380205306730539ac8c77dec1d0aa9aa9743a0773c731d300a19f1acad2c7ceb41ee3e603c636fc805c8b7f12a370136ed94bd84b03d3430aca6601",
gasLimit: 4712388,
gasUsed: 0,
hash: "0xd793c4be0804f87d21d42c694e762c6cb6277ef1fcdbf20f67970f5f82e0d16b",
logsBloom: "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
miner: "0x0000000000000000000000000000000000000000",
mixHash: "0x0000000000000000000000000000000000000000000000000000000000000000",
nonce: "0x0000000000000000",
number: 183000,
parentHash: "0x2233532f7554029162c085888efd944009dd0fc86bdb97314dc0c1c2d37f58cf",
receiptsRoot: "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
sha3Uncles: "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
size: 609,
stateRoot: "0x8425418849819297a2f8f8391f16445928a42f415362bd17cf9282e8bbff8093",
timestamp: 1494755487,
totalDifficulty: 357271,
transactions: [],
transactionsRoot: "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
uncles: []
}
I've found transactions at Block n. 188880.
Also, I'm waiting the full sync of the Testnet Rinkeby to check the Block n. 1830000.
Try to change block number and check if there are transactions in it.
eth.getTransaction(eth.getBlock(188880).transactions[0])
Should work ;)