Vb.net

1 I am new to vb.net
2º i have many graphic files excel 1 each and I want to export to pdf in vb.net
I have the chart in vb.net xlWB.ActiveSheet.ChartObjects ( 1) .Chart
but I try to export with your api and adding reference xltoolbox - 64.dll gives have error " Search Results

You can not add a reference not valid assembly or component xltoolbox.dll "
3º my English is google translator