Steps I undertook to debug the failure of PVSS2COOL:

=== Offline DB ===

checkDcs commands:
{{{
./checkDcsDb -sGMT 20100713:120000 -eGMT 20100715:180000 -d 'ATLPIXLCS3:L2_B20|L2_B20_S1_A6_M4A.fsm.currentState' --dumpDP
./checkDcsDb -sGMT 20100713:120000 -eGMT 20100715:180000 -d 'ATLPIXLCS3:L2_B20|STATUS_L2_B20_S1_A6_M4A.fsm.currentState' --dumpDP 
}}}

After changing the query from name to alias:
{{{
./checkDcsDb -sGMT 20100713:120000 -eGMT 20100715:180000 -d 'L2_B20_S1_A6_M4A%' --dumpDP 
}}}

=== COOL DB ===

First get the date in unix time:
{{{
date +"%s" -d "Tue Jul 13 15:00:00 CEST 2010"
date +"%s" -d "Thu Jul 15 18:00:00 CEST 2010"
}}}

And here is the command to query the COOL DB:
{{{
AtlCoolCopy.exe "oracle://ATLAS_COOLPROD;schema=ATLAS_COOLOFL_DCS;dbname=COMP200;user=ATLAS_COOL_READER_U;password=LMXTPRO4RED" pixdcs.root -root -folder /PIXEL/DCS -ts 1279026000 -tu 1279209600
}}}

Then I used CoolDcsCheck to loop over the trees.