Hi
The data in your last table does not have any CR. Also, SUBSTITUTE is case sensitive.
Try
<b>Excel 2010</b><table cellpadding="2.5px" rules="all" style=";background-color: #FFFFFF;border: 1px solid;border-collapse: collapse; border-color: #BBB"><colgroup><col width="10px" style="background-color: #DAE7F5" /><col /><col /></colgroup><thead><tr style=" background-color: #DAE7F5;text-align: center;color: #161120"><th></th><th>A</th><th>B</th></tr></thead><tbody><tr ><td style="color: #161120;text-align: center;">1</td><td style=";">Balance</td><td style=";">Formula</td></tr><tr ><td style="color: #161120;text-align: center;">2</td><td style=";">30 CR</td><td style="text-align: right;;">-30</td></tr><tr ><td style="color: #161120;text-align: center;">3</td><td style=";">50 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">4</td><td style=";">3500 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">5</td><td style=";">50 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">6</td><td style=";">3300 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">7</td><td style=";">3333 CR</td><td style="text-align: right;;">-3333</td></tr><tr ><td style="color: #161120;text-align: center;">8</td><td style=";">1 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">9</td><td style=";">70 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">10</td><td style=";">3500 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">11</td><td style=";">3500 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">12</td><td style=";">3312 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">13</td><td style=";">60 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">14</td><td style=";">90 CR</td><td style="text-align: right;;">-90</td></tr><tr ><td style="color: #161120;text-align: center;">15</td><td style=";">3200 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">16</td><td style=";">84 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">17</td><td style=";">15 DR</td><td style=";"></td></tr><tr ><td style="color: #161120;text-align: center;">18</td><td style=";">3150 DR</td><td style=";"></td></tr></tbody></table><p style="width:3.6em;font-weight:bold;margin:0;padding:0.2em 0.6em 0.2em 0.5em;border: 1px solid #BBB;border-top:none;text-align: center;background-color: #DAE7F5;color: #161120">Sheet1</p><br /><br /><table width="85%" cellpadding="2.5px" rules="all" style=";border: 2px solid black;border-collapse:collapse;padding: 0.4em;background-color: #FFFFFF" ><tr><td style="padding:6px" ><b>Worksheet Formulas</b><table cellpadding="2.5px" width="100%" rules="all" style="border: 1px solid;text-align:center;background-color: #FFFFFF;border-collapse: collapse; border-color: #BBB"><thead><tr style=" background-color: #DAE7F5;color: #161120"><th width="10px">Cell</th><th style="text-align:left;padding-left:5px;">Formula</th></tr></thead><tbody><tr><th width="10px" style=" background-color: #DAE7F5;color: #161120">B2</th><td style="text-align:left">=IF(<font color="Blue">RIGHT(<font color="Red">A2,2</font>)="Cr",SUBSTITUTE(<font color="Red">LOWER(<font color="Green">A2</font>)," cr",""</font>)*-1,""</font>)</td></tr></tbody></table></td></tr></table><br />