It is possible that no capacity is allocated to you even though you have offered a higher surcharge than the final price of the auction. Usually, that is because you requested too high a minimum amount of capacity which could not be supplied from the leftover capacity after the highest bidders received their allocation. If that's the case, then a lower bidder, whose minimum could be supplied, might take your place (Kill Procedure). Since the Uniform Price Algorithm sets the final price by the lowest offer, the auction might thus end at a lower price.
For more information, please consult Uniform Price Algorithm.