st42_download not charge the complete file

[kacper1972]

I bought st42_download plugin. I installed it according to instructions, but when the customer gets meil, he gets only the zip file where it says:

^{<br />
<b>Warning</b>:  readfile(kurs_joomla_25_tom1.zip) [<a href='function.readfile'>function.readfile</a>]: failed to open stream: No such file or directory in <b>/home/m56810re/public_html/videoporady/plugins/vmcustom/st42_download/st42_download.php</b> on line <b>332</b><br />}

How to fix it?