I have tested on my local. Please double check your code with my reply. Here is the result:

The Rest API document: https://msdn.microsoft.com/en-us/library/azure/mt163564.aspx
PUT:
https://management.azure.com/subscriptions/{subscription ID}/resourceGroups/jatestgroup/providers/Microsoft.Storage/storageAccounts/akingtt?api-version=2016-01-01
Header:
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhb......
Content-Type: application/json
Host: management.azure.com
Content-Length: 443
Request Body
{
"location": "East Asia",
"tags": {
},
"properties": {
"encryption": {
"services": {
"blob": {
"enabled": true
}
},
"keySource": "Microsoft.Storage"
}
},
"sku": {
"name": "Standard_RAGRS"
},
"kind": "Storage"
}
Please note:
1) "Kind" is Required in version 2016-01-01 and later.
2) "accessTier" is Required when kind = 'BlobStorage'.
Forbidden when kind = 'Storage'.
3) prior to version 2016-01-01, 'sku' was called 'accountType' and was found under the 'properties' envelope.