# Cannot use stream.WaitAsync() due to ambiguity between methods

**URL:** <https://forum.commonvisionblox.com/t/cannot-use-stream-waitasync-due-to-ambiguity-between-methods/291>\
**Category:** .Net API\
**Created:** [December 13, 2017, 1:11pm UTC](https://forum.commonvisionblox.com/t/cannot-use-stream-waitasync-due-to-ambiguity-between-methods/291 "2017-12-13T13:11:58Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![andrea.annovi](https://avatars.discourse-cdn.com/v4/letter/a/bc8723/32.png) [@andrea.annovi](https://forum.commonvisionblox.com/u/andrea.annovi)\
**Post date:** [December 13, 2017, 1:11pm UTC](https://forum.commonvisionblox.com/t/cannot-use-stream-waitasync-due-to-ambiguity-between-methods/291/1 "2017-12-13T13:11:58Z")

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I tried to run the example provided in [Getting Started with CVB.Net](https://forum.commonvisionblox.com/t/getting-started-with-cvb-net/246/10) but I got the following error when using WaitAsync

| Severity | Code | Description | Project | File | Line | Suppression State |
| --- | --- | --- | --- | --- | --- | --- |
| Error | CS0121 | The call is ambiguous between the following methods or properties: ‘Stemmer.Cvb.Async.AcquisitionExtensions.WaitAsync(Stemmer.Cvb.Driver.IAcquisition)’ and ‘Stemmer.Cvb.Async.AcquisitionExtensions.WaitAsync(Stemmer.Cvb.Driver.IAcquisition)’ | | | | |

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<div class="post-metadata">

**Author:** ![parsd](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.commonvisionblox.com/parsd/32/7_2.png) [@parsd](https://forum.commonvisionblox.com/u/parsd)\
**Post date:** [December 13, 2017, 1:14pm UTC](https://forum.commonvisionblox.com/t/cannot-use-stream-waitasync-due-to-ambiguity-between-methods/291/2 "2017-12-13T13:14:41Z")

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Did you reference the _Stemmer.Cvb.Async.dll_? This assembly has been integrated into the current version of _Stemmer.Cvb.dll_ which might produce the error you see.

It should be gone if you remove the reference to _Stemmer.Cvb.Async.dll_.

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<div class="post-metadata">

**Author:** ![andrea.annovi](https://avatars.discourse-cdn.com/v4/letter/a/bc8723/32.png) [@andrea.annovi](https://forum.commonvisionblox.com/u/andrea.annovi)\
**Post date:** [December 13, 2017, 2:38pm UTC](https://forum.commonvisionblox.com/t/cannot-use-stream-waitasync-due-to-ambiguity-between-methods/291/3 "2017-12-13T14:38:03Z")

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I removed the reference to the Stemmer.Cvb.Async.dll. in the project configuration but I kept

```auto
using Stemmer.Cvb.Async;

```

and It works.

Thanks

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<div class="post-metadata">

**Author:** ![illusive](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.commonvisionblox.com/illusive/32/61_2.png) [@illusive](https://forum.commonvisionblox.com/u/illusive)\
**Post date:** [December 13, 2017, 4:48pm UTC](https://forum.commonvisionblox.com/t/cannot-use-stream-waitasync-due-to-ambiguity-between-methods/291/4 "2017-12-13T16:48:32Z")

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The `Stemmer.Cvb.Asyn` has been moved from the (no longer existing) _Stemmer.Cvb.Async.dll_ to the _Stemmer.Cvb.dll_, therefore it is ok to leave the `using Stemmer.Cvb.Async` in place. The reason why we had this namespace in its own dll in the first place was to have the possibility to use _Stemmer.Cvb.dll_ with .Net 4.0 as well, but we recently reconsidered this choice.