Runtime Error COPA Report KE30 - Assign_Length_0

Question

Dear users,
As ABAP is unknown terrain for me, I stumbled upon an error which I can't seem to bypass.  I do not know wheter this is the right forum to ask the question, so if I'm wrong, please do correct me.
Current situation
1. I've added a user def COPA Characteristic to the operating concern X.
2. I've made a realignment run to fill table CE40001 (prof segments)
3. Ive created a report (with form) where the report uses the field (point 1) as a drill down object.
When running this report, I immediatly get the error 'Assign length 0' - in program "SAPMKCBE", module "SEIG_POSITIONIEREN"
When looking at the error it stumbles at understanding code.  It seems that
1. looking for value in table  'field_tab', which is CE10001
2. field "Reffl"
But as I've checked the table, this field does not exist.  So this is where I'm stuck;
Allready thanks for any help that you can provide!
Ben
74           IF SY-SUBRC EQ 0.
75             IF L_S_LCOL_CHAR-DIMPR EQ DIMPR_L  OR
76                L_S_LCOL_CHAR-DIMPR EQ DIMPR_KL OR
77                L_S_LCOL_CHAR-DIMPR EQ DIMPR_LK.
78               IF FIELD_TAB-FIENM NE SEIG-FNAM.
79                 READ TABLE FIELD_TAB WITH KEY
80                                      FIENM = SEIG-FNAM BINARY SEARCH.
81               ENDIF.
82               I = FIELD_TAB-REFLL.
83               ASSIGN FELD1(I) TO <TEXT>.                   "#EC *
84             ELSE.
85               ASSIGN FELD1(20) TO <TEXT>.
86             ENDIF.

Answer 1

I found the issue regarding this problem. In customizing for the COPA characteristics, you have to define the default display for this characteristic in the COPA Report. This option can be set to "Long Text".
As it seems, this field is (in my case) not activated, and it can't be activated.  Nor can it be maintained.
As a result the report searches for 'long text - REFLL' which doesn't exist.
solution:
Change default view for the characteristic AND completly rebuild your report.  Since SAP doesn't read this value (default dispay) dinamicly, but only once while creating the report.
regards and thanks for no help
hope I could be of assistance to anybody else