Solution to problem

Ok so this is what you should do:
1.create a seriescollectio n cause you have several series (plots/lines) in one excel chart
2.create the seperate series
3. assign the values for each series.

Code:
Excel.SeriesCollection seriesCollection;
Excel.Series series1, series2;

//this create the seriescollection and series
seriesCollection = xlChart.SeriesCollection(misValue)
...