'disappointing expectations' is correct and usable in written English.
You can use it to talk about a situation in which someone's expectations were not met. For example: The team was unable to win the championship, disappointing expectations across the city.
Global retail sales at Burberry's established stores rose 2%, disappointing expectations in the City of a 3% rise.
Industrial output fell by 0.4% over the month, matching August's drop and disappointing expectations that production would be flat.
Separately, the European Union statistics agency, Eurostat, said that industrial production in the 16-country euro area was unchanged in July from June, disappointing expectations for an increase.
The annual rate of growth in retail sales slipped slightly to 3.6% in June from 3.7% in May, again disappointing expectations of an increase to 3.9%.
Separate figures from the ONS showed construction output, which accounts for around 6% of the economy, fell in October, disappointing expectations of a rise.
German unemployment figures continued to rise, disappointing expectations that unusually mild temperatures in March would lead to the creation of new jobs.
All in all, a mixed bag, disappointing high expectations but worth checking out.
In addition to disappointing those expectations for July, the Labor Department revised down the payroll figures for May and June.
Apple sold 5 million of its iPhone 5 in its launch weekend alone, at the time disappointing analysts' expectations of 10 million sales.
Chinese banks extended 513bn yuan ($80.66bn) in net new yuan loans in October, disappointing analyst expectations and down 51% on the previous month's 1.05 trillion yuan.
Both new building work and repair and maintenance jobs declined, disappointing City expectations of a 0.7% increase after a 1.8% increase in construction output in September.
