Call transfer between 2 Hipath 4000 systems

[vph4k]

2 Hipath 4000's are networked via ECMAV2. Xpressions is connected to Hipath A, incomming calls via expressions can be transfrred to extension of both Hipath A & B. The problem is that once the incomming call is answered in Hipath A and then the extension from Hipath A consults the call to extension in Hipath B, it can't transfer the call??says not possible and call rings back to the same extension of Hipath A??

outgoing call from extension in Hipath A can transfer the same call to extension in Hipath B.

In trace it shows as normal call clearance??