# Problem with imported Keras LSTM model

**URL:** <https://community.konduit.ai/t/problem-with-imported-keras-lstm-model/114>\
**Category:** DL4J\
**Created:** [January 30, 2020, 4:24pm UTC](https://community.konduit.ai/t/problem-with-imported-keras-lstm-model/114 "2020-01-30T16:24:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![tintin](https://avatars.discourse-cdn.com/v4/letter/t/ed655f/32.png) [@tintin](https://community.konduit.ai/u/tintin)\
**Post date:** [January 30, 2020, 4:24pm UTC](https://community.konduit.ai/t/problem-with-imported-keras-lstm-model/114/1 "2020-01-30T16:24:40Z")

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i have a question. I have a basic LSTM model with first layer being Masking layer. the input shape is (None, sequence length, feature length). I used KerasModelImport.importKerasSequentialModelAndWeights() to import the model, the model seems to be fine. Except when i create a sample input, it gives me nullpointer exception. Any idea why? I check the basicRNNExample case, seems like the input shape is like (None, feature length, sequence length). Does the importer take care of that?

```
Exception in thread "main" java.lang.NullPointerException
	at org.deeplearning4j.nn.layers.samediff.SameDiffLayer.activate(SameDiffLayer.java:125)
	at org.deeplearning4j.nn.layers.AbstractLayer.activate(AbstractLayer.java:257)
	at org.deeplearning4j.nn.layers.recurrent.MaskZeroLayer.activate(MaskZeroLayer.java:71)
	at org.deeplearning4j.nn.multilayer.MultiLayerNetwork.outputOfLayerDetached(MultiLayerNetwork.java:1301)
	at org.deeplearning4j.nn.multilayer.MultiLayerNetwork.output(MultiLayerNetwork.java:2419)
	at org.deeplearning4j.nn.multilayer.MultiLayerNetwork.output(MultiLayerNetwork.java:2382)
	at org.deeplearning4j.nn.multilayer.MultiLayerNetwork.output(MultiLayerNetwork.java:2373)
	at org.deeplearning4j.nn.multilayer.MultiLayerNetwork.output(MultiLayerNetwork.java:2360)
	at org.deeplearning4j.nn.multilayer.MultiLayerNetwork.predict(MultiLayerNetwork.java:2216)
	at DomainClassifier.main(DomainClassifier.java:58)

```

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<div class="post-metadata">

**Author:** ![treo](https://yyz1.discourse-cdn.com/flex035/user_avatar/community.konduit.ai/treo/32/47_2.png) [@treo](https://community.konduit.ai/u/treo)\
**Post date:** [January 30, 2020, 4:26pm UTC](https://community.konduit.ai/t/problem-with-imported-keras-lstm-model/114/2 "2020-01-30T16:26:50Z")

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An you please also post the stack trace of the exception?