Input variable into text box

I am working with an open source piece of software to send basic USB data. I am trying to get the software to recieve data and then input that data into a text box. To retrieve data entered into a text box i have used:

OutputPacketBuffer[2] = Convert::ToUInt16(tbSetpointText->Text)

However i now want to enter data that i have received into a textbox. The following does not seem to work:

Convert::ToString(tbArraySizeText->Text)=InputPacketBuffer[2]

I am not at all familiar with this language as this is a piece of software which we need to add this feature for so it can be used for lab applications.