Eomonth in Excel -

how can use function in user defined function ? cannot reference cell.

function sonxmonth()    sonxmonth = eomonth(a1,0) + 1 end func 

you need use worksheetfunction used container microsoft excel worksheet functions can called visual basic.

function sonxmonth() sonxmonth = worksheetfunction.eomonth(range("a1"), 0) end func