Problem in Azure SQL Database Basic Tier

Question

I have a WinForms Application was using Azure SQL Database (Web)
It was working fine with web version (for last 2.5 years). 
After Microsfot's new offerings of New Tiers of Azure SQL Database, 
I tried Basic Tier.
Observation for last 24 hours according to Azure Portal when Database in
BASIC state :::
Successful Connections : 2 (Max), 1.5(Avg), 3(Total)
Failed Connections : 0 (Max), 0 (Avg), 0 (Total)
Throttled Connections : 0 (Max), 0 (Avg), 0 (Total)
Deadlocks : 0 (Max), 0 (Avg), 0 (Total)
Storage : 23.38MB (Min), 23.75MB (Max), 23.47MB (Avg)
CPU Percentage : 0 (Min), 3.34 (Max), 1.14 (Avg)
Log Writes Percentage : 0 (Min), 0.05 (Max), 0.02 (Avg)
Physical Data Reads Percentage : 0 (Min), 0.01 (Max), 0 (Avg)
The WinForm Application working fine but there is some problem:
When a Report is generated (local .rdlc), the connection gives "Timeout Expired"
This problem occurs only in 25% cases (in 75% cases works fine)with same data.
If I upgrade database to Standard (S1) it works fine.
QUESTION IS :
Resource Stats show it is using very low resources.
like CPU percentage 3.34 (Max), Log Writes Percentage 0.05 (Max)
and Physical Data Reads Percentage 0.01 (Max)
Why the report not works in 25% cases in BASIC state but works in STANDARD S1 state ?
The price of Standard S1 is 8 timeshigher then BASIC
Thanks

Answer 1

Hello Fanny,
Thanks for reply.
I know it and that's why I mentioned different resource stats.
My database (BASIC) using only :
CPU Percentage :  3.34
(Max)
Log Writes Percentage :
0.05 (Max)
Physical Data Reads Percentage :
0.01 (Max)
While Microsoft says if any parameter goes beyond 80% usage then you need to upgrade tier
Please see following video on Channel 9:
Azure SQL Database and the new Database Throughput Unit 
 by Tobias Ternstrom – Principal Program Manager Lead for performance in Azure SQL Database
Thanks