insert based on value in first row

I have a fixed file that I am importing into a single column with data similar to what you see below:

ABC$        WC        11683                                    
11608000163118430001002010056788000000007680031722800315723      
11683000486080280000002010043213000000007120012669100126691      
ABC$        WC                         000000020000000148000     
ABC$        WC        11683                                    
1168101057561604000050200001234000000027020023194001231940      
54322010240519720000502000011682000000035640006721001067210      
1167701030336257000050200008765000000023610029066101151149      
11680010471244820000502000011680000000027515026398201263982

I want to split and insert this data into another table but I want to do so as long as the '11683' is equal to a column value in a different table + 1. I will then increment that value (not seen here).

I tried the following:

declare @blob as varchar(5) 
declare @Num as varchar(5)

set @blob = substring(sdg_winn_blob.blob, 23,5)
set @Num = (Cnum.num + 1)

IF @blob = @Num
INSERT INTO SDG_CWF
    (
        GAME,SERIAL,WINNER,TYPE
    )
SELECT convert(numeric, substring(blob,28, 5)),convert(numeric, substring(blob, 8, 9)),
        (Case when (substring(blob, 6,2)='10') then '3' 
              when (substring(blob, 6,2)='11') then '4' 
              else substring(blob, 7, 1)
         End),
        (Case when (substring(blob, 52,2)='10') then '3' 
              when (substring(blob, 52,2)='11') then '4' 
              else substring(blob, 53, 1)
         End)

FROM sdg_winn_blob
WHERE blob not like 'ABC$%'
else
print 'The Job Failed'

The insert works fine until I try to check to see if the number at position (23, 5) is the same as the number in the Cnum table. I get the error:

Msg 4104, Level 16, State 1, Line 4
The multi-part identifier "sdg_winn_blob.blob" could not be bound.
Msg 4104, Level 16, State 1, Line 5
The multi-part identifier "Cnum.num" could not be bound.