Error code: InvalidIntentSamplePhraseSlot -

I got the error code Error code: InvalidIntentSamplePhraseSlot when I built the model using the new skills console. The full error message is

Sample utterance "AddBookmarkIntent i am at {pageno} of {mybook}" in intent "AddBookmarkIntent" cannot include both a phrase slot and another intent slot. Error code: InvalidIntentSamplePhraseSlot - 

where {pageno} is AMAZON.NUMBER and {mybook} is AMAZON.SearchQuery

What is the error about and how can I solve it?

edit: add the JSON for the intent

{
    "name": "AddBookmarkIntent",
    "slots": [
        {
            "name": "mybook",
            "type": "AMAZON.SearchQuery"
        },
        {
            "name": "pageno",
            "type": "AMAZON.NUMBER"
        }
    ],
    "samples": [
        "i am at {pageno} of the book {mybook}",
        "save page {pageno} to the book {mybook}",
        "save page {pageno} to {mybook}",
        "i am at {pageno} of {mybook}"
    ]
}

It's not allowed to have a slot of the type AMAZON.SearchQuery in the same Utterance with another slot, in your case AMAZON.NUMBER.

Mark one of the slots as required and ask for them separately.

A little example:

Create the Intent put in the utterances and slots:

"intents": [
    {
      "name": "AddBookmarkIntent",
      "samples": [
        "I am at {pageno}"
      ],
      "slots": [
        {
          "name": "mybook",
          "type": "AMAZON.SearchQuery",
          "samples": [
            "For {mybook}"
          ]
        },
        {
          "name": "pageno",
          "type": "AMAZON.NUMBER"
        }
      ]
    }

Mark the specific slot as required so Alexa will automatically ask for it:

"dialog": {
  "intents": [
    {
      "name": "AddBookmarkIntent",
      "confirmationRequired": false,
      "prompts": {},
      "slots": [
        {
          "name": "mybook",
          "type": "AMAZON.SearchQuery",
          "elicitationRequired": true,
          "confirmationRequired": false,
          "prompts": {
            "elicitation": "Elicit.Intent-AddBookmarkIntent.IntentSlot-mybook"
          }
        }
      ]
    }
  ]
}

and create the prompts to ask for the slot:

"prompts": [
  {
    "id": "Elicit.Intent-AddBookmarkIntent.IntentSlot-mybook",
    "variations": [
      {
        "type": "PlainText",
        "value": "For which book you like to save the page?"
      }
    ]
  }
]

This is probably much easier with the skill builder BETA and not its editor because it will automatically create the JSON in the background.