Google Ads API - Optimize Campaign By Specific Conversion Action(s) - google-api

Question

I am using Google Ads PHP library to create Campaign.
I created almost any type of campaigns but didn't manage to optimize them by specific Conversion Actions.
For example:
I have created 3 different Conversion Actions:
customers/[CUSTOMER_ID]/conversionActions/[CONVERSION_ACTION_ID_0]
customers/[CUSTOMER_ID]/conversionActions/[CONVERSION_ACTION_ID_1]
customers/[CUSTOMER_ID]/conversionActions/[CONVERSION_ACTION_ID_2]
Then I created a Campaign:
customers/[CUSTOMER_ID]/campaigns/[CAMPAIGN_ID]
I set bidding strategy to MAXIMIZE_CONVERSIONS and then tried to set Conversion Actions to optimize to.
This is my code snippet:
$campaign->setMaximizeConversions(
new CommonMaximizeConversions([
'target_cpa' => $this->convert()->micros(1)
])
);
$campaign->setSelectiveOptimization(
new SelectiveOptimization([
'conversion_actions' => [
'customers/[CUSTOMER_ID]/conversionActions/[CONVERSION_ACTION_ID_0]',
'customers/[CUSTOMER_ID]/conversionActions/[CONVERSION_ACTION_ID_1]'
]
])
);
It gives me this error:
{
"message": {
"message": "Request contains an invalid argument.",
"code": 3,
"status": "INVALID_ARGUMENT",
"details": [
{
"#type": "type.googleapis.com/google.ads.googleads.v10.errors.GoogleAdsFailure",
"errors": [
{
"errorCode": {
"requestError": "UNKNOWN"
},
"message": "The error code is not in this version.",
"trigger": {
"stringValue": ""
},
"location": {
"fieldPathElements": [
{
"fieldName": "operations",
"index": 0
},
{
"fieldName": "create"
},
{
"fieldName": "selective_optimization"
},
{
"fieldName": "conversion_actions"
}
]
}
}
],
"requestId": "xbgMUFFeP4447GFW_nJrIA"
}
]
},
}
Can you tell me what I am doing wrong? Or suggest any help?.
Thanks.