Friends of InterAkt Extensions

just updated to 5.3 and have updated my includes folder but have an issue with image upload
prior to upgrade worked 100% fine now generates a 500 error
giving this error: [18-Oct-2011 09:08:49] PHP Fatal error: Class 'KT_fileUpload' not found in /home/xxx/public_html/includes/tng/triggers/tNG_FileUpload.class.php on line 185

This is driving me nuts
any ideas please

Ian,
What does line 185 look like?

"$fileUpload = new KT_fileUpload();"

I just tested it on my server with php 5.3.3 installed.