>Hi Cetin
>
>>In expression.
>
>This is the latest expression as stored in the DynamicBackColor property, I have checked for the column as an object
>
>

IIF((NOT EMPTY(v_tdocslk.iID)) AND (TYPE('THIS.colcname') = 'O' AND THIS.colcname.ENABLED AND (NOT THIS.colcname.READONLY)), goApp.nBackColorFld, goApp.nBackColorForm)

>
>also as VARTYPE()
>
>

IIF((NOT EMPTY(v_tdocslk.iID)) AND (VARTYPE(THIS.colcname) = 'O' AND THIS.colcname.ENABLED AND (NOT THIS.colcname.READONLY)), goApp.nBackColorFld, goApp.nBackColorForm)

>
>no change to the problem.
>
>Taking your idea further I found the problem, well, the application object goApp was no longer available, I was getting the application as a visual so I presumed the goApp was still existing.
>
>

IIF((NOT EMPTY(v_tdocslk.iID)) AND (TYPE('THIS.colcname') = 'O' AND THIS.colcname.ENABLED AND (NOT THIS.colcname.READONLY)), IIF(TYPE('goApp') = 'O', goApp.nBackColorFld, 0), IIF(TYPE('goApp') = 'O', goApp.nBackColorForm, 0))

>
>Thanks.

Change check for TYPE('goApp')='O' to vartype(goApp) = 'O'. The first check doesn't check if the object is NULL.