Difference between two dates

[Anik]

Hello good people, now I am reading "Definitive Guide to dax - Alberto Ferrari". The first image shows the the days between delivery dates and order dates. The 2nd image is the practice file done by me and what you can see is the negative differences. I am working with the same data been used in this book but it's not working for me It's been 3 days I am trying everything to  get the accurate result, but I failed. I can't understand what the fault is in tha dataset. For your help, I've provided the file to go it over. 

https://drive.google.com/file/d/1R43cXcP0Fa1jdgbXVvq6FhMv2HrYvSWp/view?usp=sharing  .   

[Anik]

@amitchandak , tried but same result, negative difference. 

[amitchandak · Accepted solution]

@Anik , I tried this in the file as new column , see all +ive

DaysToDeliver = if(Sales[Order Date]<Sales[Delivery Date], datediff( Sales[Order Date],Sales[Delivery Date] ,day ) ,datediff( Sales[Delivery Date] ,Sales[Order Date],day ))

[amitchandak]

@Anik , have tried datediff

example new column

new column = datediff ([order date], [Delivery Date],day)