Access has two concatenation operators (+ and &). However, the + operator is also the mathematical addition operator. Since one of your inputs is implicitly converted to numeric it is trying to sum a numeric and a string.
Either change the concatenation operators to & or explicitly cast your numeric to string data type.
Pootle is right, Access is trying to add rbs to you number. Another issue I noticed is that your password is going to be pretty odd on the first of every month (rbs-1d). I that what you were intending?
Thank you for your replies. DCKunkle, my password is even more slightly complex than that. What you see is only an idea to make the password variable.
Anyway I've just solved it. JUst change Format(Date,"dd")*2-3 to Trim$(Str$(Format(Date,"dd")*2 - 3))