通过 Laravel 应用程序发送文档时，Docusign SignHere 选项卡不显示

我正在开发一个 Laravel 应用程序，其中集成了 DocuSign 来发送文档进行电子签名。我按照官方 DocuSign API 文档设置了 JWT 身份验证并成功发送了文档。但是，当我发送文档进行签名时，文档上没有显示签名字段。

正如我提到的，我成功发送了文件，构建信封的代码如下：

    public function buildEnvelope(Request $request): EnvelopeDefinition
    {
        $fileContent = $request->file('formFile')->get();
        $fileName = $request->file('formFile')->getClientOriginalName();
        $fileExtension = $request->file('formFile')->getClientOriginalExtension();
        $recipientEmail = $request['email'];
        $recipientName = $request['name'];

        $document = new Document([
            'document_id' => "1",
            'document_base64' => base64_encode($fileContent),
            'file_extension' => $fileExtension,
            'name' => $fileName
        ]);

        $sign_here_tab = new SignHere([
            'anchor_string' => "**signature**",
            'page_number' => "1",
            'anchor_units' => "pixels",
            'anchor_x_offset' => "100",
            'anchor_y_offset' => "300"
        ]);

        $tabs = new Tabs([
            'sign_here_tabs' => [$sign_here_tab]
        ]);

        $signer = new Signer([
            'email' => $recipientEmail,
            'name' => $recipientName,
            'recipient_id' => "1",
            'tabs' => $tabs
        ]);

        $recipients = new Recipients([
            'signers' => [$signer]
        ]);

        $inlineTemplate = new InlineTemplate([
            'recipients' => $recipients,
            'sequence' => "1"
        ]);

        $compositeTemplate = new CompositeTemplate([
            'composite_template_id' => "1",
            'document' => $document,
            'inline_templates' => [$inlineTemplate]
        ]);

        return new EnvelopeDefinition([
            'composite_templates' => [$compositeTemplate],
            'email_subject' => "Please sign",
            'status' => "sent"
        ]);
    }

我已经指定了页码、一些随机坐标、锚字符串和锚单位，并期望在第 1 页的某个地方看到文本签名