tftp download is working, http - not

[mimiko]

I've put original downloaded undionly.kpxe, not my build. PXE gets an IP and downloads undionly.kpxe. I press Ctrl+B. Then issue ifopen, then chain ... to the file.
in dhcp:
next-server 10.10.0.75;
filename "undionly.kpxe";

Cannot attach the image:

The file upload failed. Please choose a valid file and try again. Error details: There was a problem moving the uploaded file to its destination.

Its 237KB jpeg image.