i followed the instructions in article id 912375. Iadded registrykeyto change info storedatabase to 25 GB I "restarted the MSexchange Is service. From the services.msc. I checked the event viewer id 1216 and it still says my db size limit 18 gb

Hi, Difficult to say what the problem is - the procedure should increase the database size limit. Did you check once more that you changed to correct key in the registry?? Leif

Please compare the Private-GUID in registry and take LDP dump for all Information store and compare the ObjectGuid and find out for which store you have increased the database.