XIRR with potentially blank cells in the range

[Nixhex11]

Guys,
I've built a financial model for projects that range in length and thus have had to build in the flexibility to handle this. In the dates portion of my cash flow within the model, I have formulas dragged over for 16 years max but the cells will only populate if the project is ongoing and will be blank if it is over (depending on user inputs).
I'd like to have an XIRR calculation built in but I get an #NUM! error due to my blank cells. I will need to cover the entire range since it's impossible to predict how long each project will be. Is there a formula that detects the range of <>"" cells and then a way to do an xirr calculation on just those? Any help would be appreciated!

Thanks!

 

[Nixhex11]

Figured it out - named both ranges (cash flows and dates) using =offset(origin cell, 0,0, 1, count(range)). Then the formula was =xirr(cashflows, dates).