Hi Sukanya,
Are you using Solution Manager 7.1 SP08 or SP10 or any other SP level ??
In case if you ae using SP10 and you are not able to assign logical component to the solution , check the below mentioned points :
1. Check if your logical component is visible in LMDB. In case not, then run tcode LMDB_LC_MIG to migrate the logical component to LMDB.
2. Check if "Assigned Product version/ product instance is correctly maintained for your logical component.
3. Check the technical system asignment with the productive client.
If all these are fine, you will be able to assign it to solution.
Regards,
MK