Not able to upgrade my lumia 525 from win 8.1 to win 10.

[Arib_123]

I am using Lumia 525 with Lumia Denim
I have downgraded my lumia 525 from windows 10 to windows 8.1 using nokia software recovery tool.And now again i want to roll back to win 10 but while selecting insider fast in windows insider and after accepting the agreement it is showing that we cannot configure your device.I want to know that why it is showing this message as previously i have successfully upraded my lumia 525 to win 10.Please help me.

 

[milkyway]

Lumia 525 is not eligible for Windows 10 Mobile, sorry