I cannot resolve #Name? error in Access

using ms access office 365 version 1707 (build 8326.2096)

i have simple form has field called dob based on column in database

i want put calculated field next dob show persons age on specific date (31st aug 2017)

i put text box on form , on "control source" field of "data" tab added following:

=int((datediff("d",[dob],dateserial(2017,8,31))/365.25))

this gives me #name? error in text box

i experimented following:

=int((datediff("d",now(),dateserial(2017,8,31))/365.25)) - ie removed reference dob field - worked

=int(datediff("d",dateserial(2008,6,12),dateserial(2017,8,31))/365.25) - checked access can date maths - worked

[dob] - checked see if access see field - worked

wtf - access can see field cant use in formula - or missing something???

thanks

tim

name of control? try renaming control other dob

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