Back button doesn't work on one page only.

I'm using a "Back" button on my pages. The code works for all except one. The following is on the page that I leave and then want to go back to.

<input type="button" name="Button1" class="style3" value="Lockout/Tagout" onClick="window.open('lockout_tagout.html')">

When I use the following script on the Lockout/Tagout page it doesn't work.

<input name="GoBack" type="button" class="style3" onClick="javascript:history.go(-1)" value="PREVIOUS PAGE">

Could someone suggest a solution or remedy for my problem?

You opened a new window...
There is nothing to go back too...