Your problem is you are checking for two conditions, not one. Sumif can
handle only one condition.

If you have Excel 2007, you can use:
=sumifs(c:c,b:b,"<="&ac10,b:b,"="&ad10)

If not, you can use Sumproduct, but you can't use an entire column.
Something like:
=sumproduct(--(b2:b1000<=ac10),--(b2:b1000=ad10),c2:c1000)

Regards,
Fred.

"Jane" wrote in message
...
I am trying to add values in one column, if the second column matches the
criteria. This is what I have written and I know this is wrong. Can anyone
please help.

SUMIF(B:B,"<=AC10 and =AD10",C:C)

Thank you