Formula field Calculation Used in another formula

Formula field Calculation Used in another formula

Hello! 

I' m having issues trying to show the price after date selection. 

* I have to dates ( arrival and departure ) 
* I have a formula field (total days) that calculate the days difference ( everything working so far) 
* I want to have another field(Price total) that shows the price depending on how many days in (total days)

I tried to go to workflow and add a new action that says If total days is 1, set field value (Price toal) to 590.
It didn't work, so I tried to do this with another field (a random text field) and it works. 

Someone have any idea what I do wrong/how to make this happend? 

Thanks
Andreas