Access crosstab query update field value by Dcount -

2 tables in access 2013

table users, store users info

yyyymm | employee id | email | name | logincount

table log, store website login time

yyyymm | userid | logintime

i want update logincount field in table users count logintime when [employee id] = [userid] , user.[yyyymm] = log.[yyyymm]. codes can not work.

update users set users.[logincount] =  dcount("log.[logintime]","log","[userid] = user.[employee id] , [yyyymm] = user.[yyyymm]"); 

it says "...unknown..." error.