single row resulset

in ssis execute sql task i want to keep my result in variable 

----select count(*) from tab----this is my query 

this will give for example 10 ....i used single row resultset  but  its throwing error like 

variable "aa": "The type of the value being assigned to variable "User::aa" differs from the current variable type. Variables may not change type during execution. Variable types are strict, except for variables of type Object.
.