Seems this is a script for SL... The line "else llSay(0, "secondlife:///app/agent/" + (string)userkey + "/inspect " + ringnotice);" cant work in OS. There are better door bells in HG.
I got 2 warnings..the other one was with the sound.
I altered to llPlaySound(llGetInventoryName(INVENTORY_SOUND, 0), 10.0);
and deleted the "string bellsound = llGetInventoryName(INVENTORY_SOUND,0);"...so this Error didnt exist anymore.
Edit: I deleted also the "who" in this line. Now it works: if (publicshout == FALSE) llOwnerSay(userkey + " " + ringnotice);
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