that's because after your ampersand, you drop out of the string and then have a - ... which means subtract... so it tries to convert your string to a double to perform the arithmetic operation... but since the string can't be converted to a double, the error results.

Going out on a limb, I'm going to guess that what you're trying to do is concatenate the ID with the company name with a - in the middle, right?

Try this:
Code:
strsql &= " ( CustomerID & ' - ' & CompanyName ) as [Companyname]"
changed the " to ' around the -

-tg