How to correctly push transaction?

What's up! Wink

I'm currently coding a Bitcoin-Transaction-System on my Website. (via bitcoinjs-lib)
Now I'm kinda stuck with pushing the transaction.
Can anyone tell me what exactly I have to push?
It's weird because I generate a Hex which works fine if I push it manually via http://tbtc.blockr.io/documentation/api
But as soon as I try to push via code the whole thing just dies.

Code:

Failed to push transaction. -> {"status":"error","data":"TX is missing","code":400,"message":"Please see API documentation on how to POST tx hex as json."}

Code:

$.ajax({
url: "http://btc.blockr.io/api/v1/tx/decode",
type: "post",
data: {
hex: transactionHex
},
success: function(response) {
decodedHex = response;
console.log(decodedHex);
document.getElementById('baseDiv').innerHTML += "

Decoded Hex: " + transactionHex;
},
error: function(xhr) {
console.log("Failed to decode Hex. -> " + xhr);
}
});

$.ajax({
url: "http://btc.blockr.io/api/v1/tx/push",
type: "post",
data: {
hex: decodedHex
},
success: function(response) {
console.log("Transaction pushed. " + response);
},
error: function(xhr) {
console.log("Failed to push transaction. -> " + xhr.responseText);
}
});

Can anyone give me a few pointers what could be the problem?

Thanks so much! <3
Cheerz~