How to establish new R1 - BCV connections

We have local BCV's setup so that FDR can back them up without impacting the production vols. I've recently added production vols and tried to establish a link from spare BCV vols to the new prod vols.
I used this JCL -
//STEP1 EXEC PGM=EMCTF
//SYSIN DD *
GLOBAL NOCHKO
ESTABLISH 1,6588-658B,647C-647F
Which worked as this query shows -
14:31:54 BCVM003I 6588 08EB 647C 07DF 0 0 INUSE EST 08EB
but somewhere in the night it went back to AVAIL ?
07:20:38 BCVM003I 6588 08EB 647C 07DF 0 0 AVAIL 08EB
Any thoughts ? insults ? hope ?
Thanks
Bruce