PHP正则表达式字符串格式化聊天对话框错误preg_replace（）

I'm formating for a chatting dialog bellow:

• Dalvik: Lorem ipsum dolor sit amet
• Jenni: Suspendisse facilisis pretium ante,
• Dalvik: Vivamus feugiat dui ut libero rhoncus nec porttitor velit posuere.
• Jenni: Aenean porttitor ipsum eu metus adipiscing
• Dalvik: (Sed vehicula: magna vitae nulla
• Jenni: sed dui quam, vitae consectetur dui.
• Jenni: Curabitur vulputate ante :)

The bold text above ; it make error in my replace statment:

$name = self::getNameFromMessage($textFormat);
$color = self::getNewTextColor();
$replacement = "<br/><font color='$color'>$name</font>:";
$textFormat = preg_replace(
           $pattern = "/$name :\s/i", //find $name in $textFormat and set text color
           $replacement, 
           $subject = $textFormat
);

Error: preg_replace() [function.preg-replace]: Compilation failed: missing ) at offset 15

Can you suggest me a better regex string?

The error was caused by not quoting your regex, in your example, the regex finds a (, then it expects to find a closing ). If you want to match a literal () or other regex meta-characters, you need to quote your regex:

$pattern = preg_quote("/$name :\s/i");