highcharts - Highstocks, line missing but data is there -

i've been playing around highstocks while , reason 1 of lines has disappeared when zooming in, yet still visible once zoomed out. still shows dot once hovering on including data belongs it.

needless i'm pretty clueless went wrong, suggestions great.

zoomed in:

zoomed out (hard see red line there)

ps. website can found here skami.net

your series contains doubled values same data, example:

    [1368450000000, null],      [1368450000000, 117.200050354004],      [1368451800000, null],     [1368451800000, 117.599990844727],     [1368453600000, null],     [1368453600000, 117.710151672363] 

which not allowed in highcharts. remove point , working fine.