Write empty value through PCO

Hi,

I have a tag on my OPC server with datatype String.

When I write an empty value to the tag through PCo I always get the error: "Invalid tag value for x".

Writing a space works but this is not good because the PLC will interpret this differently.

How can I write an empty value to a tag?

I am using Kepware OPC and PCO 15.0.0.1959

Thanks