Ok Ill give it a try
=IF(AND(A5=I5,ISERR(SEARCH(C5,"T")),C5,{Don't Know})
I5 = Contract name (i.e. MAR08 -APR08)
"T" in column C means there was a trade at this price, SEARCH would return an error if no "T" was found.
The FALSE part of the IF should contain the original value in J5.
i.e. if...