passing a MaxLength ux:Property to ux:Class

Any ideas on why the following throws a “Sequence contains no elements” error?

The problem lies within the {Property this.MaxLen} usage, since replacing it to an integer triggers no error. Tried experimenting with different property types, such as float4 and float, no luck.

<App Theme="Basic">

    <Panel ux:Class="TextMultiLine" Margin="0,0,0,3" Background="#fff" Height="50">
        <string ux:Property="Text" />
        <float ux:Property="MaxLen" />

        <TextInput
            FontSize="16"
            PlaceholderText="Click to edit"
            Value="{Property this.Text}"
            ActionStyle="Send"
            TextColor="#000"
            CaretColor="#000"
            PlaceholderColor="#666"
            IsMultiline="true"
            Margin="10,0,10,0"
            MaxLength="{Property this.MaxLen}"
            >
        </TextInput>
        <Rectangle Height="1" Fill="#ddd" Alignment="Bottom" />
    </Panel>

    <ClientPanel Background="#333">
        <TextMultiLine Text="Testing" MaxLen="20" />
    </ClientPanel>
</App>

Solved by changing the property definition to <int ux:Property="MaxLen" />

Note to self: variable types are important. More clear error messages would help.