my model is this:
namespace org.acme.mynetwork
asset Sensor identified by assetID {
    o String assetID
    o String Frequency
    o String longitude
    o String latutide
    o String name
    --> Spectrum range
}
participant Spectrum identified by SpectrumId {
    o String SpectrumId
    o String Spectrumval
}
transaction SpectrumChange {
    --> Sensor sensor 
    --> Spectrum newrange
}
My sample.js file contains:
/**
 * Track the trade of a commodity from one trader to another
 * @param {org.acme.mynetwork.SpectrumChange} Change - the spectrum to be processed
 * @transaction
 */
function Spectrumupdate(spectrumChange) {
    spectrumChange.sensor.range = spectrumChange.newrange;
    return getAssetRegistry('org.acme.mynetwork.Sensor')
        .then(function (assetRegistry) {
            return assetRegistry.update(spectrumChange.sensor);
        });
}
When I test is I am getting this error: Error: Object with ID 'assetID:0138' in collection with ID 'Asset:org.acme.mynetwork.Sensor' does not exist 
How can I solve this?