Mollie applicationfee's - api

Question

for a customer I need to charge an applicationFee for each order that has been processed on their site from the sub customers. The whole code is working with authentication and everything.
But from the moment I'm adding:
'applicationFee' => $applicationFee
to the call I receive this error:
Error executing API call (422: Unprocessable Entity): Unable to process application request for this account. Documentation: https://docs.mollie.com/guides/handling-errors"
The content of "$applicationFee" is correct, that I was able to check already.
The $shop_mollie_data->profile_id containts the different websiteprofileId's found on the Mollie dashboard.
$provider = new MollieConnectProvider($request, $clientId, $clientSecret, $redirectUrl);
$newAccessToken = $provider->getRefreshTokenResponse($shop_mollie_data->refresh_token);
$mollie = new MollieApiClient();
$mollie->setAccessToken($newAccessToken['access_token']);
$payment = $mollie->payments->create([
'amount' => [
'currency' => 'EUR',
'value' => (string) (sprintf("%.2f", $order_total))
],
'description' => ucfirst($shop->name) . ' - Order #' . $order_nm,
'webhookUrl' => $url_callback,
'redirectUrl' => $url_success,
'method' => 'bancontact',
'locale' => $language_id,
'metadata' => [
"order_id" => $ref,
"shop id" => $shop->id
],
'profileId' => $shop_mollie_data->profile_id,
'testmode' => true,
'applicationFee' => $applicationFee
]);