Table Formula Throws VALUE Error at Bottom of Column

[NorthbyNorthwest]

Hi, everyone. I have a formula copied down a column "DC", rows 6 - 89. Formula works until row 84 when a VALUE error occurs. The formula is simple. It's in column "DC" and references the cell to the immediate left, in column "DB."" Why would a formula that worked for 70+ rows suddenly throw an error? Attached is a pic of the table.

The formula in column "DC" is =IF($DB6="","",SUBSTITUTE(SUBSTITUTE(LEFT($DB6,SEARCH("]",$DB6)),"[",""),"]",""))

Copied down the errors start in row 84, =IF($DB84="","",SUBSTITUTE(SUBSTITUTE(LEFT($DB84,SEARCH("]",$DB84)),"[",""),"]",""))

There is also a formula copied down column "DB". It is =IFERROR(IF([@Employee]="","",CONCAT(tblDetails[@[Err1]:[Err23]],tblDetails[@[Err30]:[Err46]])),""). If I remove this formula from a cell in column "DB" and replace with a real value, then the formula in "DC" works. So, is there a problem with the formula in column "DB"? Is yes, what is it?

Any assistance would be appreciated. Thanks in advance.

 

[Peter_SSs]

Cheers. Thanks for the comments.