apache win32 chuncked vulnerability

[theunknown]

hi
i was scaning a remote system with acunatix vulnerability scanner and i found the apache chunked encoding vulnerability .tried to exploit it with metasploit but it always says that it failed.i checked the vulnerability manually and found that it exists.anyone can help me on this issue.i mean there must be the firewall blocking metasploits attempt to exploit the vuln.is there a sol'n to all this problem??