Unable to apply CellStyle from style defined in ResourceDictionary - wpf

Question

I have defined some styles for a datagrid, but the styles for CellStyle, ColumnHeaderStyle and RowStyle is not applied. Others styles like the background color and rowheight are working fine.
The default style are based on FirstFloor.ModernUI's datagrid styling
If I put the styles directly on the data-grid then everything works fine. also at design-time
<DataGrid
Style="{StaticResource BilagDatagridStyle}"
ColumnHeaderStyle="{StaticResource BilagsColumnHeaderStyle}"
CellStyle="{StaticResource DataGridCellNoInteractionStyle}"
RowStyle="{StaticResource DataGridRowNoInteractionStyle}"
Without it's not working
<DataGrid
Style="{StaticResource BilagDatagridStyle}"
This is the styles that I am using:
<Style x:Key="BilagsColumnHeaderStyle" TargetType="{x:Type DataGridColumnHeader}">
<Setter Property="FontSize" Value="12"/>
<Setter Property="FontWeight" Value="SemiBold"/>
<Setter Property="HorizontalAlignment" Value="Left"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type DataGridColumnHeader}">
<ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
Margin="4,3"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="DefaultReadOnlyGridStyle" TargetType="{x:Type DataGrid}" BasedOn="{StaticResource {x:Type DataGrid}}">
<Setter Property="CanUserAddRows" Value="False"/>
<Setter Property="CanUserDeleteRows" Value="False"/>
<Setter Property="CanUserSortColumns" Value="False"/>
<Setter Property="AutoGenerateColumns" Value="False"/>
<Setter Property="VerticalAlignment" Value="Stretch"/>
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="IsReadOnly" Value="True"/>
<Setter Property="SelectionMode" Value="Single"/>
<Setter Property="HeadersVisibility" Value="Column"/>
<Setter Property="Width" Value="Auto"/>
<Setter Property="RowHeight" Value="30"/>
<Style x:Key="BilagDatagridStyle" TargetType="{x:Type DataGrid}" BasedOn="{StaticResource DefaultReadOnlyGridStyle}">
<Setter Property="CellStyle" Value="{StaticResource DataGridCellNoInteractionStyle}"/>
<Setter Property="RowStyle" Value="{StaticResource DataGridRowNoInteractionStyle}"/>
<Setter Property="ColumnHeaderStyle" Value="{StaticResource BilagsColumnHeaderStyle}"/>
It's the Template part in the BilagsColumnHeaderStyle that's overwritten. I have been trying to write a separate Template but I cant get the syntax right. Maybe if I split the styling and the template part it will work?
Any suggestions are much appreciated