I'm at a loss as to why that is happening. The button works fine, clicking right through to PayPal when it is viewed in an HTML editor. There is also a similar type of link set up on WileyJohn's blog for his book which clicks through to the intended target image. The only thing I can suggest is to try using a text link version of the PayPal donate button. It would look something like the following:
Code:
<a href="https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=DNRVS743EHLPQ">Make a Donation</a>
It would appear in the blog column as follows: Make a Donation
How this link is made is fairly easy; on the page where you generate your PayPal button code, there is also an option for an email link. The email code is easily turned into an HTML type of link by inserting it between "" in the following code:
Code:
<a href="">Make a Donation</a>