I have called Matlab functions from C# using COM objects. It runs but on multiple calls it gives an exception while instantiating matlab Engine Interface through COM.

//for instantiating MATLAB Engine Interface through COM

```
MLApp.MLAppClass matlab = new MLApp.MLAppClass();
```

Exception it gives:

Unable to cast COM object of type 'MLApp.MLAppClass' to interface type 'MLApp.DIMLApp'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{669CEC93-6E22-11CF-A4D6-00A024583C19}' failed due to the following error: The RPC server is unavailable. (Exception from HRESULT: 0x800706BA).

I'm unable to figure this out. Any help will be appreciated.

asked on Stack Overflow May 4, 2013 by user2134669

I had the same problem. I was using 2 private functions, creating two different matlab objects inside that functions. Then I made the matlab object global problem solved(as below). But your problem might not be the same.

```
public partial class Form1 : Form
{
#region ----> Global Variables
// Create the MATLAB instance
MLApp.MLApp matlab = new MLApp.MLApp();
```

answered on Stack Overflow Mar 31, 2016 by Cemaleddin Simsek • edited Mar 31, 2016 by Alexei - check Codidact

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