UTM & COLT not working on a CISCO-Switch (State UP, Link DOWN)

Hey all,

we´re expericing the following strange behaviour:

2 UTM SG430 in A/P-HA are connected to a HP-Procurve 2810-24G Switch. This Switch then connects via SX-SFP to the ACCEDIAN-Router delivered from COLT with our 1 GBit WAN-Line.

So far so good, everything works.

Now we need to switch to new CISCO-Switches (9200L) as the HP is getting too old.

i connected the HP to the CISCO for transition, then moved the UTM Ports from HP to CiSCO -> everything works fine

BUT: as soon as i also move the fibre from the SFP in HP to the CISCO, the link goes up but the UTM says in dashboard "State: UP, Link: DOWN"

Odd thing is: if i connect the fibre coming from the accedian-Router to a Fibre/Copper-Converter using the same SFP and then patch this into a Gig-Port on the cisco -> the link goes up !

TCP Window scaling as in Rulez is activated. MTU on eth-interface for COLT is on 1500 ...

Any ideas where to look ?

Kind regards,

Markus