php使用echo就报错....

刚开始学php，写了一段文字生成图片的代码。现在发现不能将text传至php里，而且就算不传参。直接在php里定义$ment = $_POST['text'_] 也会报错：图像xxx因存在错误无法显示，肯定不是字体的问题，我快疯了..谁能帮帮我...代码如下
index.html:

<code>             <title>Logo Generater</title>                    </code>

https://www.gxlcms.com/logo generate.php:

<code><!--?php$ment = 'What are you 弄啥类？'$ment = $_POST['text'];echo $ment;echo strlen($ment);$im = imagecreate(450,50);$white = imagecolorallocate($im,0,0,0);#imagecolortransparent($im,$white); $black = imagecolorallocate($im,255, 255,255);imagettftext($im,26,0,15,40,$black,'E:\xampp\htdocs\test\simsun.ttc',$ment);header("Content-type:image/png");imagepng($im);?--></code>

谢谢了...
-------------------------16:35更新-----------------------
谢谢帮助我的人~(づ￣ 3￣)づ
还有个问题 能不能像这张图一样，点击OK，传参给PHP，之后还在这个界面显示图片
以下是新代码~

<code>             <title>Logo Generater</title>                </code><form action="https://www.gxlcms.com/logo generate.php" method="post"><code>        <h2>Logo Generater</h2>        <h2>wirte by Yates WANG</h2>        <label for="ment">Company name:</label>        <input type="text" name="ment" id="ment">        <input type="submit" name="submit" id="submit" value="OK">        <br>        <br>        <img src="https://www.gxlcms.com/logo generate.php">            </code></form>

<code> <!--?php#$ment = 'What are you 弄啥类？';$ment = $_POST['ment'];#echo strlen($ment);#$len = strlen($ment) * 30;$im = imagecreate(400,50);$white = imagecolorallocate($im,0,0,0);#imagecolortransparent($im,$white); $black = imagecolorallocate($im,255, 255,255);imagettftext($im,26,0,15,40,$black,'C:\Windows\Fonts\simsun.ttc',$ment);header("Content-type:image/png");imagepng($im);imagedestroy($im);?--></code>

再次感谢！