file not found on desktop

In my script I create a pdf file from a webpage and place it on my desktop. I use this command to find it and create and alias and I later move it to another folder.
The file is on the desktop and appears to be the exact same name as the saved confimrationof but I get this error message.

set confirmationof to (path to desktop folder as text) & confirmationo & confirmationofp & ".pdf"
alias confirmationof

If I rerun this script with the file already on the desktop I get a dialogue box that asks if I want to replace the file. If I click replace, the command works?
What is going on and how can I fix this?

I guess you use a shell command without proper escaping the special characters

I don’t know shell commands at all. I have tried to use them but you can’t really tell what is going on since there is no feedback. I have removed all the colons and commas and it still won’t make an alias out of it.

Any idea’s for applescript?