DWarn 0x0E697B77 refers to the DLL throwing an exception, usually one that was not properly handled. LabVIEW caught the exception in order to prevent the DLL from crashing and reported it to the user. This is often accompanied by DWarn 0x50CBD7C1 and error 1097 or 1517 from the output of the Call Library Function Node.
In the case of the DLL throwing an exception, the Call Library Function Node will generate error 1097. This can mean that the function parameters were improperly configured, the DLL performed an illegal operation such as dereferencing a null pointer, or a more code-specific problem occurred that generated an exception within the DLL.
If instead the Call Library Function Node generates error 1517 when called, the calling convention is not configured correctly. Change the configuration of the Call Library Function node to "stdcall" or "cdecl" as appropriate (see the Setting Calling Convention section of the Configuring Call Library Function Node
Ensure that the DLL works in the development language and in LabVIEW in a simpler implementation. In addition, ensure that the function parameters are configuring properly.