locking Cells

Hello Experts,

I'm blocking a cell of Excel and do as follows:

1) Lock function Excel Cells with "protect"

2) Lock the book on the role EPM> Options sheet-> Protection

The problem is that when I update the sheet, all locks are lost, I have this problem too with validation of data.

I'm in version 10.0 NW, SP 20. NET 3.5

Has anyone had this problem and solved it like?

Regards

Carolina