I have a problem with captcha when uploading the project on server.

for example 3 or 4 captcha file do not upload and i see error when uploading that files. but for my second site, i do not have this problem.

the errors are:

/public_html/captcha/imcpa_u4v.gif  ------ error

/public_html/captcha/imcpa_vmu.gif  ------ error

/public_html/captcha/imcpa_xly.gif  ------ error

/public_html/captcha/imkeys.php

the errors also is attached in a picture

please give me a solution.