Solved the issues by seeing in another situation that
pdf file is not displayed or created properly.
When your pdf report or excel report do not open,
eg.:-
just blank screen and no pdf display
or just giving in the screen
%PDF-1.3
3 0 obj
<</Type /Page
/Parent 1 0 R
/MediaBox [0 0 595.28 841.89]
/Resources 2 0 R
/Annots [<</Type /Annot /Subtype /Link /Rect [50.00 806.00 155.79 790.00] /Contents (1) /NM (0001-0000) /M (D:20100104234236) /Border [0 0 0] /C [] /A <</S /URI /URI (1)>> /H /I>><</Type /Annot /Subtype /Link /Rect [50.00 787.00 102.91 779.00] /Contents (1) /NM (0001-0001) /M (D:20100104234236) /Border [0 0 0] /C [] /A <</S /URI /URI (1)>> /H /I>><</Type /Annot /Subtype /Link /Rect [120.00 787.00 182.27 779.00] /Contents (1) /NM (0001-0002) /M (D:20100104234236) /Border [0 0 0] /C [] /A <</
The answer is quoted from Joe for reference
Enter the config.php file with an editor and set
the $go_debug variable to 0
(when this is 1 FA prints the instructions to the pdf engine instead of the pdf file).
It really works!!!