Mbr slots

It is my hard disk original state:
Local Disk(C:) 450 GB
RECOVERY(D:) 15 GB

but system has 2 others as:
system 199 MB
HP_tools 104 MB

I want to create at least 1 other local disk, so I resized (C:) to 120 GB and 330GB volume remained as free. (I use partition wizard 5)
When I clicking on an Unallocated space and click on "create" reply this error:
"Partition Wizard cannot create a partition at here. There are no free MBR slots on the disk."
now I don't know how to make MBR slots available.