shortcode didn't show permalink correctly when mouseover it

For example, if I use
[wpdm_package id='10']
When you mouseover the link
It will show http://www.mysite.com/blog/?wpdmdl=10
not http://www.mysite.com/?wpdmdl=10

Two links are no problem for download file.

I already set the rewrite rule in .htaccess, other permalinks are showing correctly as http://www.mysite.com.
Just wondering that if I need make some modify?
Thanks a lot.