The below can help you in understanding in detail bro
What happens during the SID generation ?
- Records are selected from the activation queue
- The selected records are used to build SID data packages. Each of the SID data packages
- contains characteristic values for one InfoObject
- has a predefined maximum size of 10.000 characteristic values
- is processed either serially or in parallel according to the settings for the activation
- Missing SID values lead to
- the creation of SID values, if the DTP option “Further processing without master data" is set
- error messages in the monitor, if the DTP option “No Further processing without Master data” is set
Typical Errors that occur during SID generation
- BRAIN070:
- No SID found for value '...' of characteristic ...
- BRAIN060, BRAIN290:
- Value '...' (hex. '...') of characteristic ... contains invalid characters.
Possible Solutions for 'No SID found for value .... of characteristic' (BRAIN070)
- Compare with values in SID table
- There is an Important DTP setting, "Type of Data Update to Data Targets"
- If you set this indicator, the system terminates activation if master data is missing and produces an error message.
- If you do not set this indicator, the system generates any missing SID values during activation.
Possible Solutions for Issues with invalid characters, such as BRAIN 290
- Check the Hex value - use SAP Note 173241.
- Check if lowercase letters are allowed for the mentioned InfoObject in tcode RSD1.
- You have 3 options to correct the data:
- Correct the Data in the source system
- Correct the data in the PSA
- Write a routine to catch the incorrect characters
This is the link bro 
SID generation during DSO request activation - SAP NetWeaver Business Warehouse - SCN Wiki