Anycubic Photon - Crooked print

Hi everyone,
I’m new with 3d printing and I’ve bought the printer in the object.
All the first prints goes well (anycubic logo, the boat benchy with different resins, and so on).
Now I’m in trouble. Quite all the prints are crooked. After few layers, the upper plate tilts and all the print is no more straight.
I’ve this problem with all the resin, and quite all the dimensions of the object, with or without supports.
I’m sure to have locked well the upper plate. About the parameters, i think to use them well as I use parameters found on the net.
I would like to add a photo to better describe the problem but I do not know how to do.
Anyway, can you help me, please?
Have you GoT any suggestion?
Thanks!!!
Stefano
Attachment 15683