What are you trying to do ? Changing the Boot Partition - EasyBCD - NeoSmart Technologies Wiki ?
If so, the restriction is part of the Microsoft boot architecture.
Only primary partitions can be active, and the MBR searches for the active partition to begin the boot process.
The OS can be loaded from a logical drive, but the boot files that do the loading must be in a primary.
If you want the boot files to be with the OS, then you must install the OS in a primary, or use a Partition Manager to reconfigure your HDD.
EasyBCD is not a partition manager. It can't convert your HDD.