I edited the acad.pat file and added new hatch patterns, deleted al the standard predefined hatches, so far so good, but now i get the message "error reading pattern file". I located the problem and it has everything to do with the predefined standard "ANGLE" hatch pattern. If i put this hatch back in the file everything works perfect and no errors. If i change hatch but keep same name everything works. When i the move the hatch to the end of the file it still works. I found out that when i hatch it always starts with the angle hatch so i guess there is alink somewhere that tells autocad to look for the angle hatch first. And this is exactly my question, how can i make the acadiso.pat work without any of the standard patterns without any error, can anyone help me with this?

Please, verify syntax of file and check hatch patterns for duplicity.

already done that, no problems. the problem occurs when you delete the "angle" hatch from the standard file as when just installed.