urgent!!!!How to write excel formula (checking data from two different sheets) : I have a formula in Sheet6 to look up a value from sheet5 and return it, but sometimes, if values are not in sheet5, I want it to check in sheet7. 

sheet6 and sheet7 have same pattern in all column, only columns have different values.

How can I rewrite the formula in sheet 6 inorder to check data in sheet 5 first and if data were not found, then sheet7 will be automatically match ? 

***oringial formula in sheet 6***
=IF(ISNA(INDEX(Sheet5!$A$4:$AG$30,MATCH($C$25,Sheet5!G4:G30,0),2)),"",INDEX(Sheet5!$A$4:$AG$30,MATCH($C$25, Sheet5!G4:G30,0),2))

Thanks for help. 

