## Summary Calling a property setter via late binding or DispID may fail for some properties. If you pass a Variant by reference or a Variant containing a Dispatch, the flag passed to IDispatch.Invoke changes from DISPATCH_PROPERTYPUT to DISPATCH_PROPERTYPUTREF. However, some property setters require DISPATCH_PROPERTYPUT. The solution is to pass the flag as the sum of these values. ## System Information - **Operating system:** Windows ## Example Project I've included an example that demonstrates this issue using MSXML. [test.zip](/uploads/79f211b924d13b3f7bd81bc78f87724e/test.zip) ## Possible fixes The solution is to pass flag as sum of DISPATCH_PROPERTYPUTREF and DISPATCH_PROPERTYPUT. Patch attached. [comobj_propsetfail.patch](/uploads/1cff8c90fcad2286801061b21e25a206/comobj_propsetfail.patch)