Transceiver placement issue

Is there any guru who can help to place more than one transceivers in one GXB block?

I tried to design two 2 channel transceivers in one GXB block that has 4 channels. Quartus II fitter always fails to place them with following error message,

Error (167005): Can't assign I/O pad "gxb_tx6" to PIN_H4 because this causes failure in the placement of the other atoms in its associated channel

Error (167009): Quartus II software cannot combine the following GXB Central control unit(s) due to inconsistent parameters and/or input connections

Error (21087): Input port "DPRIOIN" must be driven by the same source

Info (21090): Atom "cyclone4gx_2ch:inst1|c4gx_2ch:c4gx_2ch_inst|c4gx_2ch_alt_c3gxb:c4gx_2ch_alt_c3gxb_component|cent_unit0" is driven by source "cyclone4gx_2ch:inst1|altgx_reconfig:altgx_reconfig_inst|altgx_reconfig_alt_c3gxb_reconfig_1801:altgx_reconfig_alt_c3gxb_reconfig_1801_component|altgx_reconfig_alt_dprio_v5k:dprio|dprioin~1"

Info (21090): Atom "cyclone4gx_2ch:inst2|c4gx_2ch:c4gx_2ch_inst|c4gx_2ch_alt_c3gxb:c4gx_2ch_alt_c3gxb_component|cent_unit0" is driven by source "cyclone4gx_2ch:inst2|altgx_reconfig:altgx_reconfig_inst|altgx_reconfig_alt_c3gxb_reconfig_1801:altgx_reconfig_alt_c3gxb_reconfig_1801_component|altgx_reconfig_alt_dprio_v5k:dprio|dprioin~1"

it looks like i violate the law that only one reconfig instance could be designed for one block. But when removed one it still says error. and here is the message,

Critical Warning (167080): GXB Central Management Unit (CMU) cyclone4gx_2ch:inst|c4gx_2ch_nb:c4gx_2ch_nb_inst|c4gx_2ch_nb_alt_c3gxb:c4gx_2ch_nb_alt_c3gxb_component|cent_unit0 is not connected to a GXB reconfig logic block, but the RX offset cancellation feature requires that it must be

Is there any design example which places more than one independent transceiver in one GXB block?

Appreciated!

Yaoting