SSRS timed out. Waiting period before the operation is completed, or the server is not responding

I have a report solution with multiple reports. Until now, I could not add a SPROC based dataset without problems. However, when I try to add the last dataset and use SPROC for its query type, when I click Refresh Fields, I get the following error: Timeout. The wait period expires before the operation is completed or the server is not responding.

I tested the database connection in the properties of the data source> Modify> Test connection and it works fine.

I increased the timeout to 100 in the following areas:

• The connection string for the data source, which is - Connect Timeout = 100
• Tools> Options> Database Tools> Query and View Constructors. Cancel long request set to 100.
• Tools> Options> Database tools> Table and database designers> Checked 'Override Connection String time-out value for the table designer Updates. Transaction timeout after set to 100

SPROC works great in an SQL database. It takes about 55 seconds.

Any other ideas? Thank.

UPDATE: now I can not add any data set using SPROC. I even thought that SPROC work fine in SQL !!!!!!