Error when assigning SID: Action VAL_SID_CONVERT , InfoObject 0REF_KEY3

Greetings Gurus,

yesterday i noticed this error:

"Error when assigning SID: Action VAL_SID_CONVERT , InfoObject 0REF_KEY3

Value 'Più doc.2013-2014 ' (hex. '0050006900F900200064006F0063002E003200300031003300') of characteri "

I understood that there are some characters not supported by BW so i did this:

1. delete the request from DSO.

2. PSA and edit error records.

3. save the data in the PSA.

4. load the data again and activate the DSO.

Unfortunatly, after reactivating the DSO, i'm  experiencing again the same error in the same request:

"Error when assigning SID: Action VAL_SID_CONVERT , InfoObject 0REF_KEY3

Value 'Più doc.2013-2014 ' (hex. '0050006900F900200064006F0063002E003200300031003300') of characteri "

I checked again the PSA but this time 0REF_KEY3 is correct, it hasn't the wrong char, so i can't understand how to solve this issue since i 've already edited the PSA.

Anyone has any idea on  how i could solve this ISSUE?

Thanks for your time

Elena