Error calling range in Excel table causing crash -

complete vba newbie here.

i'm trying adapt code found on ron de bruin's site (bmail9.html specific tutorial/example). code straightforward enough , works in de bruin's file.

i able adapt work column name [days until liquidation due] within excel table [tbl_countdown] on secondary worksheet [interface2] of workbook. (this link file in question.1) however, when tried shift focus column name [days until liquidation due] in excel table [tbl_interface] in primary worksheet [interface], code has failed spectacularly: crashes excel (2013). (this link screenshot of error message on opening file.) , re-open it, error message generated. , more not (although not 100% of time), crashed excel regardless of whether choose 'end' or 'debug'.

 option explicit private sub worksheet_calculate()     dim formularange range     dim countdownrange range     dim notsentmsg string     dim mymsg string     dim sentmsg string     dim mylimit double     dim countdownfeedbackoffset double
  
notsentmsg = "not sent" sentmsg = "sent"  'below mylimit value run macro mylimit = 1  'set range formulas want check 
  
this line fails , crashes everything
  
set formularange = worksheets("interface").range("tbl_interface[liquidation in]")     countdownfeedbackoffset = 3
  
on error goto endmacro: each formulacell in formularange.cells     formulacell         if isnumeric(.value) = false             .offset(0, 3).value = "not numeric"             mymsg = "not numeric"         else             if .value < mylimit                 mymsg = sentmsg                 if .offset(0, countdownfeedbackoffset).value = notsentmsg                     call mail_adv_liq_reminder                     'call mail_with_outlook1                 end if             else                 mymsg = notsentmsg             end if         end if         application.enableevents = false         .offset(0, 3).value = mymsg         application.enableevents = true     end next formulacell 
  
exitmacro:     exit sub
  
endmacro:     application.enableevents = true
  msgbox "some error occurred." _      & vblf & err.number _      & vblf & err.description 

end sub

to clear, 'ask' here figure out how call named range (rather hard-coding column name) code robust future additions or substractions of columns interface table. i'd know why it's failing enter image description herespectacularly it's crashing excel.