"500" Status: Internal Server Error

I added Money CCK field with a content type but when I ran cron for indexing content, following is the error I am getting when:

Indexing failed on one of the following nodes: 22, 24, 25, 33, 32, 30, 29, 28, 26, 34, 35, 27, 31 
"500" Status: Internal Server Error


Error 500 

HTTP ERROR: 500Error while creating field 'ps_cck_field_price{type=sdouble,properties=indexed,stored,omitNorms,omitTermFreqAndPositions,sortMissingLast}' from value ''

org.apache.solr.common.SolrException: Error while creating field 'ps_cck_field_price{type=sdouble,properties=indexed,stored,omitNorms,omitTermFreqAndPositions,sortMissingLast}' from value ''
at org.apache.solr.schema.FieldType.createField(FieldType.java:200)
at org.apache.solr.schema.SchemaField.createField(SchemaField.java:94)
at org.apache.solr.update.DocumentBuilder.toDocument(DocumentBuilder.java:246)
at org.apache.solr.update.processor.RunUpdateProcessor.processAdd(RunUpdateProcessorFactory.java:60)
at org.apache.solr.handler.XMLLoader.processUpdate(XMLLoader.java:139)
at org.apache.solr.handler.XMLLoader.load(XMLLoader.java:69)
at org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(ContentStreamHandlerBase.java:54)
at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:131)
at org.apache.solr.core.SolrCore.execute(SolrCore.java:1316)
at org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:338)
at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:241)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1089)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:365)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:712)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:211)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:285)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:502)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:835)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:641)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:208)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:378)
at org.mortbay.jetty.bio.SocketConnector$Connection.run(SocketConnector.java:226)
at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:442)
Caused by: java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
at java.lang.Double.parseDouble(Unknown Source)
at org.apache.solr.util.NumberUtils.double2sortableStr(NumberUtils.java:100)
at org.apache.solr.schema.SortableDoubleField.toInternal(SortableDoubleField.java:49)
at org.apache.solr.schema.FieldType.createField(FieldType.java:198)
... 27 more