This issue is solved in v2015.1.840.0

Thanks for your answer :). I will create the issue.

I tried it and i worked just fine. The same solution applies to AreaSeries too.

Thanks a lot Mohd. I will try it and post the result here.

To follow up on my answer. I tried switching

DataFieldX = "MN",
DataFieldY = "Value",

to

DataFieldX = "Value",
DataFieldY = "MN",

and removing
categAxis.ItemsSource = chartvm.DateValues;
categAxis.LabelField = "MN";

The same error occued again.

Sorry for my late answer.

I am not calling the ToDouble method myself. It is called internally. Is it posible that the string value DateValue.MN is being parsed as a double?? That is the only thing I can think of that makes sense.

Can anybody reproduce the problem?