Cannot Register Mirror when Apache mod_security is enabled

I tried to register our mirror in Philippines but when I tried to click the
submit button it displays:

The following entries were submitted:
>
> Submission-Type: new
>
> Site: mirror.rise.as
> Type: leaf
> Archive-architecture: ALL amd64 armel armhf hurd-i386 i386 kfreebsd-amd64
> kfreebsd-i386 mips mipsel powerpc s390x sparc
> Archive-ftp: /debian/
> Archive-http: /debian/
>
> A proper project/trace directory was not found on the HTTP server (under
> /debian/).
>
> The trace directory needs to be fully synced from upstream, and need a
> local tracefile named after the site name.
>
> The error message returned was: 403 Forbidden
>
> Please have a look at the documentation
> <http://www.debian.org/mirror/ftpmirror>.
>
> If you don't understand this error message, please contact us.
>
> Entry not submitted!
>

The Apache mod_security was enabled. Below was the error log:

[Wed Jun 10 16:07:33 2015] [error] [client 82.195.75.65] ModSecurity:
>> Access denied with code 403 (phase 2). Operator EQ matched 0 at
>> REQUEST_HEADERS. [file
>> "/etc/httpd/crs/base_rules/modsecurity_crs_21_protocol_anomalies.conf"]
>> [line "47"] [id "960015"] [rev "1"] [msg "Request Missing an Accept
>> Header"] [severity "NOTICE"] [ver "OWASP_CRS/2.2.9"] [maturity "9"]
>> [accuracy "9"] [tag "OWASP_CRS/PROTOCOL_VIOLATION/MISSING_HEADER_ACCEPT"]
>> [tag "WASCTC/WASC-21"] [tag "OWASP_TOP_10/A7"] [tag "PCI/6.5.10"] [hostname
>> "mirror.rise.as"] [uri "/debian/project/trace/ftp-master.debian.org"]
>> [unique_id "VXfwRSviBkoAAHFYkxAAAAAJ"]
>
> [Wed Jun 10 16:07:34 2015] [error] [client 82.195.75.65] ModSecurity:
>> Access denied with code 403 (phase 2). Operator EQ matched 0 at
>> REQUEST_HEADERS. [file
>> "/etc/httpd/crs/base_rules/modsecurity_crs_21_protocol_anomalies.conf"]
>> [line "47"] [id "960015"] [rev "1"] [msg "Request Missing an Accept
>> Header"] [severity "NOTICE"] [ver "OWASP_CRS/2.2.9"] [maturity "9"]
>> [accuracy "9"] [tag "OWASP_CRS/PROTOCOL_VIOLATION/MISSING_HEADER_ACCEPT"]
>> [tag "WASCTC/WASC-21"] [tag "OWASP_TOP_10/A7"] [tag "PCI/6.5.10"] [hostname
>> "mirror.rise.as"] [uri "/debian/project/trace/mirror.rise.as"]
>> [unique_id "VXfwRiviBkoAAHFakxYAAAAL"]
>
>

How can I register our mirror site with mod_security enabled?