Lowess normalization problem

Hello, I have installed the last version of MS-dial 5.1
I have set all my samples in analytical order and I have a total of 18 QCs.
When I try to normalize the samples it doesn't allow me to normalize using Lowess.
I can't click on "Normalize" and I don't know if there is something I have to do before the normalization.
Can someone help me with this issue?
Thank you