自定义Drupal模块中的未定义变量

I write custom Drupal module. Want show field_myear in contents. With the following:

<div class="right">
                                <h4>'.$m_detail->title.'</h4>
                                <div class="section">'.$field_myear.'</div>
                                <div class="description">
                                    <div

But when refresh page, get this error:

Notice: theme_news()/home/domains/site.net/public_html/sites/all/modules/site/theme.module dosyasının 1247 satırı) içinde Undefined variable: field_myear.

How can i fix it?

Follow the execution of your page. Step through it line by line. When you are outputting the HTML shown above, you haven't got a value set for field_myear. You need to be sure you are setting it prior to trying to output it - or you need to check your variable name to make certain that it is correct and doesn't have a typo in it.