spell number error - "#NAME?" - help!

I have loaded the visual basic programing to use the spell number function.
I use the spell number function in a column referencing the cell in the
previous column - example: cell f2: = spell number (e2). I filled column f
so that what number is entered in any cell of column e willl be spelled out
in the next cell in column f. The problem: I use this as a template and
copy and past data (ex: $5.00) from another sheet within the same workbook
into column e then merge with MS Word to print checks. With no warning and
no understanding why, sometimes after creating the data in the sheet, copying
it, then pasting, I have a template that will not spell number and produces a
"#NAME?" error in the f column. The formula still reads correctly, the
visual basic module is still indicated in the visual basic editor. I have no
idea why? Any ideas???