Hi here is a table to check your results with.
http://www.solarhotusa.com/products/controls/files/Resistor-table-Pt1000.pdf
I used the equation in a spread sheet and it works fine.
Do your calculations step by step.
Tom........ 
Hi here is a table to check your results with.
http://www.solarhotusa.com/products/controls/files/Resistor-table-Pt1000.pdf
I used the equation in a spread sheet and it works fine.
Do your calculations step by step.
Tom........