What is the syntax error in my SQL?

my sql is sql = "UPDATE tbl_employees SET Username_= """ & TextBox1.Text & """, Password_= """ & TextBox2.Text & """, Temporary=" & False & " WHERE Username_ = """ & EmployeeLogin.loginusername & """ AND Password_ = """ & EmployeeLogin.loginpassword & """"

what is the syntax error? thanks for any help