Exchange API Order Entry : Keep getting REQUIRED_TAG_MISSING - invalidTag=52

Exchange/Pro API
1

I have logged in successfully, and trying to send a NewOrderSingle message (type = “D”).

But I keep getting rejected with 58=REQUIRED_TAG_MISSING - invalidTag=52

I’m following the format exactly for SendingTime (tag 52). What’s going on here?
YYYYMMDD-HH:MM:SS.sss

Sending:
"8=FIXT.1.1 9=168 35=D 11=<order_id> 34=2 38=1 40=2 44=10 49=<api_key> 52=20240312-19:19:24.327 54=1 55=BTC-USDC 56=Coinbase 59=1 1138=1 10=175 "

Receiving:
"8=FIXT.1.1 9=208 35=j 49=Coinbase 56=<api_key> 34=3 50=TEST 52=20240312-19:19:24.366174 369=1 45=-2147483648 372=D 379=<cloid> 380=0 58=REQUIRED_TAG_MISSING - invalidTag=52 10=000 "

2

Found the issue, the ordering of header tags matters

8, 9, 35, then 52, 49, 56, then the rest of the tags