Having trouble sending templates through WhatsApp Cloud API

Question

I created a complete signup template with cloud API. I've put custom fields like name select date. template is approved and it's showing on my CRM. but when I sent this template I got an error

{
    "error": {
        "message": "(#131000) Something went wrong",
        "type": "OAuthException",
        "code": 131000,
        "error_data": {
            "messaging_product": "whatsapp",
            "details": "Something went wrong"
        },
        "fbtrace_id": "Ai9oDlQLfTBFgpIh748V1fO"
    }
}

but if I create a simple template and add a website button with my website link it works with no issue.

I need to send form message using the WhatsApp template