Dataset Timeout expired error Problem in SSRS

Hi all,
I am getting one typical error when I try to create a dataset based on SQL query in SSRS.
I am using SSRS 2008 R2 and when I try to execute the query for creating dataset its giving timeout expired error. The same problem is persisting even after increasing the connection timeout time to 10 minutes. The error is coming when the number of rows retrieved is more than 100000 and also for SELECT * FROM ......
I am able to retrieve the data in SSMS within a fraction of seconds.

Thanks and Welcome for all suggestions:)