TT scores better than mate in 1 or worse than checkmate ,how

[MahmoudUthman]

I think the cause of the wrong behavior is this coupled with me defining Mate0=ShrtMax , which makes scores higher than Mate0 wrong when stored in the tt using as "Short" , when I lowered Mate0 the problem disappeared

So you mean 16-bit integer overflow? That would be an explanation

yes