Why not IPv5?

I heard there was a draft version of IPV5 in the past that was planned to be launched for streaming protocols but it was not successful.  So in order to avoid confusion IPV6 was named with the next number. 

IP version 5 was skipped in favor of IPv6

IPv5 never became an official protocol. It is known as IPv5 started out under a different name: Internet Stream Protocol, or simply ST.

The ST/IPv5 internet protocol was developed as a means of streaming video and voice data by Apple, NeXT, and Sun Microsystems, and it was experimental.

With the development of IPv6 and its promise of nearly unlimited IP addresses and a fresh start for the protocol, IPv5 itself was never transitioned to public use in large part because of its 32-bit limitations.

IPv5 used IPv4's 32-bit addressing, which eventually became a problem. The format of IPv4 addresses is the ###.###.###.### format, which is made up of four numerical octets (a unit of digital information in computing consisting of eight bits), with each set ranging from 0 to 255 and separated by periods. This format allowed for 4.3 billion internet addresses;

For more information about IPv5, you can refer to the following post:
Information about IPv5