How to call a contract from scatter

Question

I want to make a transaction with Scatter but I'm getting this error

function callContract(){

    const account = scatter.identity.accounts.find(x => x.blockchain === 'eos');
    const transactionOptions = { authorization:[`${account.name}@${account.authority}`] };

    eos.transaction(['mycontractyo'], push => {
        push.mycontractyo.reg('somestring', '1234567890123456')
     })
    .then(trx => console.log('trx', trx))
    .catch(err => console.error(err))     
}

The Error I get is

code: 402
isError: true
message: "You are trying to sign a request with an account that isn't currently linked or doesn't exist in the user's Scatter"
type: "account_missing"

I can't figure out where to pass in account or transactionOptions