title: bioMart Package error: error in function useDataset
body: <p>I am trying to use the biomaRt package to access the data from Ensembl, however I got error message when using the useDataset() function. My codes are shown below.</p>
  <pre><code>library(httr)
  listMarts()
  ensembl = useMart(&quot;ENSEMBL_MART_ENSEMBL&quot;)
  listDatasets(ensemble)
  ensembl = useDataset(&quot;hsapiens_gene_ensembl&quot;,mart = ensemble)
  </code></pre>
  <p>When I type useDataset function i got error message like this:</p>
  <pre><code>&gt; ensembl = useDataset(&quot;hsapiens_gene_ensembl&quot;,mart = ensembl)
  Ensembl site unresponsive, trying asia mirror
  Error in textConnection(text, encoding = &quot;UTF-8&quot;) : 
    invalid 'text' argument
  </code></pre>
  <p>and sometimes another different error message showed as:</p>
  <pre><code>&gt; ensembl = useDataset(&quot;hsapiens_gene_ensembl&quot;,mart = ensembl)
  Ensembl site unresponsive, trying asia mirror
  Error in textConnection(bmResult) : invalid 'text' argument
  </code></pre>
  <p>it seems like that the mirror automatically change to asia OR useast OR uswest, but the error message still shows up over and over again, and i don't know what to do.</p>
  <p>So if anyone could help me with this? I will be very grateful for any help or suggestion.</p>
  <p>Kind regards Riley Qiu, Dongguan, China</p>