As ferriz points out, you either need to use single-quotation around eloquamail in the span tag instead of double quotations or you can do without any marks as in my original reply above. I don't use any and I've never run into any problems. If you use a double-quotation mark Eloqua thinks that that is the end of the URL and so your link and code breaks.
Tracking merged links can be tricky -- search Topliners for more discussion on this -- but if you control the landing page, you should be able to get metrics there.