Need help with Create Network, other calls work ok

[#1]

Hi, can't seem to create network (powershell, but regardless). Creating IP reservation works, so generally script works. Here are examples of working and not working:

Example of working: 
Set IP reservation on existing network:
Invoking: https://infobloxapp.com/wapi/v2.9.7/fixedaddress?_return_fields%2B=ipv4addr,mac,name,comment
Headers:
Key: Content-Type Value: application/json
Key: Authorization Value: Basic xxxxxxxxxxxxxxxxxxxxxxxxx
Body: {
"comment": "Added by Automation (C\u0026C)",
"name": "DSTESTHOST",
"mac": "00:00:00:00:00:00",
"ipv4addr": "172.16.0.8"
}
Response:
_ref : fixedaddress/ZG5zLmZpeGVkX2FkZHJlc3MkMTcyLjE2LjAuOC4wLi4:172.16.0.8/default
comment : Added by Automation (C&C)
ipv4addr : 172.16.0.8
mac : 00:00:00:00:00:00
name : DSTESTHOST
network_view : default

Example of NOT working:  
Create New Network:
Invoking: https://infobloxapp.com/wapi/v2.9.7/network?_return_fields%2B=network&_return_as_object=1
Headers: 
Key: Content-Type Value: application/json
Key: Authorization Value: Basic xxxxxxxxxxxxxxxxxxxxxxxx
Body: {
"comment": "new network",
"network": "10.7.128.0/24"
}
invoke-InfobloxAPI : The remote server returned an error: (400) Bad Request.
At \\cxxxxxxxx\d$\DSI_Automations\Modules\Infoblox_API.ps1:163 char:13
+ $response = invoke-InfobloxAPI -uri $uri -method POST -body $network ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException
+ FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,Invoke-InfobloxAPI

[#2]

Grid Manager 8.5.4 if it helps