Hyperlink function reference multiple cells?

[totalnoob]

Ok so I made a lot of progress but hit some more walls. Here's what I have so far:

=HYPERLINK("url?subject="&SUBSTITUTE(A11," ","%20"&"&description=test......", "test")

The substitute part allows me to remove spaces from the text in A11 so the browser will run the URL and the invite will include the spaces back in.

Now the wall... It seems that there is some kind of maximum character limit I am hitting... If I increase the amount of text in A11, the hyperlink shows up as #value. Also if I try to do anything not<=4 characters in the description field it will also show up as #value.