I am defining all my items in .items files, but you cannot mix both (UI and items files AFAIK).
Maybe my syntax helps:
Rollershutter Z_RollerSh "Rollladen [%s %%]" <blinds> (G_Num,gDiningBlinds) ["OpenState"] {channel="zwave:device:zwaveUSBCtrl:node7:blinds_control", alexa="RangeController.rangeValue" [category="EXTERIOR_BLIND", supportedRange="0:100:1", unitOfMeasure="Percent", actionMappings="Close=100,Open=0,Lower=(+10),Raise=(-10)", stateMappings="Closed=100,Open=0:99"]}
By the way: You have a typo in your definition:
[quote="mchill, post:1, topic:123227"]
`OPen=0`
[/quote]