The wingraphviz COM object refuse to load with php 4.3.10.

the sript exit because the $t_graphviz is null after loading wingraphviz

graphviz_api.php line 292 :
$t_graphviz = new COM( $this->graphviz_com_module );

Check if we managed to instantiate the COM object.

if ( is_null( $t_graphviz ) ) {

We can't display any message or trigger an error on

failure, since we may have already sent a Content-type

header potentially incompatible with the any html output.

return;
}

There is no more after updating to php 4.4.0

the problem with an empty (none image) still exist in version 1.1.0a4 if there is no relation between issues.

the following changes correct this behaviour:
edit core/graphviz_api.php

before:
if ( count( $this->nodes ) <= 1 )
return;

after:
#even if no relationship exists the graphic is now not corrupt and will show the issue itself
#if ( count( $this->nodes ) <= 1 )

return;

Fixed by removing support for wingraphviz - just use the dot/neato exe's - see snapshot/commit @ http://git.mantisforge.org/w/mantisbt.git?a=commit;h=629a6760104e5f742ad54b5a765be78d4c42eef3

Marking as 'acknowledged' not resolved/closed to track that change gets ported to master-2.0.x branch