Need help inserting text into ever 7th (blank) cell.

I have this list and I am using the following formula =IF(MOD(ROW(),7)=0,"DC/TRANSMITTAL",INDIRECT("B"&ROW()-INT((ROW())/7))) to add DC/TRANSMITTAL into the blank space between PAXGENE and ROYAL BLUE.

ROYAL BLUE
SERUM SST
RED TOP
PPT PLASMA
LAVENDER
PAXGENE

ROYAL BLUE
SERUM SST
RED TOP
PPT PLASMA
LAVENDER
PAXGENE

ROYAL BLUE
SERUM SST
RED TOP
PPT PLASMA
PAXGENE
ROYAL BLUE

When I use the above formula I get this:
ROYAL BLUE
SERUM SST
RED TOP
PPT PLASMA
LAVENDER
PAXGENE
DC/TRANSMITTAL
0
ROYAL BLUE
SERUM SST
RED TOP
PPT PLASMA
LAVENDER
DC/TRANSMITTAL
PAXGENE
0
ROYAL BLUE
SERUM SST
RED TOP
PPT PLASMA

Is there any way that I can have the 0 not appear when I use this formula.