秒表不递增

我不明白为什么这段代码在4个小时后无法度量。

    if (guildVaultRunStarter.IsRunning)
    {
        if (guildVaultRunTimer.ElapsedMilliseconds > 4 * 60 * 60 * 1000) // 4 hours
        {
            guildVaultRunStarter.Reset();
            log("Its been over 4 hours - empty bags.");
            return true;
        }
        else
        {
            log("guildVaultRunTimer.ElapsedMilliseconds = " +
                guildVaultRunTimer.ElapsedMilliseconds.ToString() + ".");
        }
    }
    else
    {
        log("Start the 4 hour guild vault countdown.");
        guildVaultRunStarter.Reset();
        guildVaultRunStarter.Start();
    }

日志显示:

[8/23/2009 12:17:21 PM]:Start the 4 hour guild vault countdown.
...
[8/23/2009 12:26:53 PM]:guildVaultRunTimer.ElapsedMilliseconds = 0.
...
[8/23/2009 12:27:26 PM]:guildVaultRunTimer.ElapsedMilliseconds = 0.

为什么总是0?