Tds credit

We had given the services in march 2011 and showed the income in A.Y.2011-12 and accordingly we claimed the tds credit. the service receiver company accepted the bill in next year and deducted tds in next year(A.Y. 2012-13)

The assessing officer argues that tds credit is not allowable for A.Y. 2011-12 because tds is not shown in 26as and also certificate is not available so tds credit is not granted.

Plz suggest me what action can be taken.