GBIC flashing green and amber, no connectivity, Need advice

[KThug]

I have just mounted a 3550 48 port switch which I would really like to integrate into my current network using the GBIC interface (the one with the yellow cord). Anyway, I have been running 3 3548's with out a problem using the "cascaded stacked" configuration, connecting the GBIC port #2 on 1st switch to the GBIC #1 port on the 2nd switch, and GBIC #2 of 2nd Switch to GBIC #1 of the 3rd switch. Now, for some reason, when I try to tie in the last switch, similar to how the other ones are set up, the GBIC activity light simply flashes green and amber.

Cisco states that this could be caused by the following:
1. Link fault.
2. Error frames can affect connectivity, and errors such as excessive collisions, cyclic redundancy check (CRC) errors, and alignment and jabber errors are monitored for a link-fault indication.

so far I have swapped the new GBIC card into another switch and verified that it works.

what is my next move in solving this issue?

any help is GREATLY appreciated!!

Thanks,

 

[lvennard]

Try this on
Switch 3 (3548)

int g0/2
switchport encapsulation dot1q

wait about a minute or so.... if it doesnt work still, try it on the switch 4 interface (g0/1) also.

Tell us what happens, then send your config of the Gig E interfaces for both switches