Resolution:
Siebel adapter throws either of below error while fetching Siebel fields.

1) adsblDTAConfiguration_RV Error [Application] AESEBL-990148 "Siebel GetBusComp error, for Repository Int Component User Key Field (An error has occurred creating business component 'Repository Int Component User Key Field' used by business object 'Repository Details'.
Please ask your systems administrator to check your application configuration.(SBL-DAT-00222))."

OR

2) adsblDTAConfiguration_RV Error [Application] AESEBL-990148 "Siebel GetBusComp error, for Repository Integration Component Key Field (An error has occurred creating business component 'Repository Integration Component Key Field' used by business object 'Repository Details'.
Please ask your systems administrator to check your application configuration.(SBL-DAT-00222))."


Please note that if you are using Siebel version 6.x, 'SiebelVersion' global variable should point to a value "6" and for any 7.x versions the value should be specified as "7" and *do not* provide the minor version details like "7.7.2.3" for the field.  
Make sure that you have provided correct value for 'Siebel Version' as per your Siebel version.